The US has confirmed that North Korea on Tuesday tested an intercontinental ballistic missile (ICBM).

Secretary of State Rex Tillerson called it a "new escalation of the threat" to the US and the world and warned that Washington "will never accept a nuclear-armed North Korea".

Pyongyang earlier said it was its first successful intercontinental ballistic missile test.

US officials believe the North may now be able to fire a missile to Alaska.

However, experts say it cannot accurately hit a target.

In response to the test over the Sea of Japan, the US and South Korea conducted a "combined [military] exercise to show our precision fire capability", Pentagon spokeswoman Dana White said in a statement.

The US also asked for an urgent meeting of the UN Security Council to discuss the issue. A closed-door session of the 15-member body is expected later on Wednesday.

• Can the US defend itself against North Korea?
• Have North Korea's missile tests paid off?
• What can the outside world do?

In a statement, Mr Tillerson said: "The United States strongly condemns North Korea's launch of an intercontinental ballistic missile.

"Testing an ICBM represents a new escalation of the threat to the United States, our allies and partners, the region, and the world."

Mr Tillerson stressed that "global action is required to stop a global threat".

And he warned that any nation that provided economic or military benefits to the North or failed to fully implement UN Security Council resolution was "aiding and abetting a dangerous regime.

What did North Korea say earlier on Tuesday?

The announcement on North Korea state television said the Hwasong-14 intercontinental ballistic missile (ICBM) test was overseen by leader Kim Jong-un.

It said the projectile had reached an altitude of 2,802km (1,731 miles) and flew 933km for 39 minutes before hitting a target in the sea.

North Korea, it said, was now "a full-fledged nuclear power that has been possessed of the most powerful inter-continental ballistic rocket capable of hitting any part of the world".

North Korea's official KCNA news agency later quoted Kim Jong-un as saying the test was a "gift" to the Americans on their independence day.

The launch, the latest in a series of tests, was in defiance of a ban by the UN Security Council.

But experts also believe that Pyongyang does not have the capacity to miniaturise a nuclear warhead that can fit onto such a missile.

How advanced is North Korea's nuclear programme?

How far could this missile travel?

The big question is what range it has, says the BBC's Steven Evans in Seoul. Could it hit the United States?

David Wright, a physicist with the US-based Union of Concerned Scientists, says that if the reports are correct, this missile could "reach a maximum range of roughly 6,700km on a standard trajectory".

That range would allow it to reach Alaska, but not the large islands of Hawaii or the other 48 US states, he says.

It is not just a missile that North Korea would need, our correspondent adds. It must also have the ability to protect a warhead as it re-enters the atmosphere, and it is not clear if North Korea can do that.

What does this test tell us? By defence expert Melissa Hanham

Once again North Korea has defied the odds and thumbed its nose at the world in a single missile launch. With the test of the Hwasong-14, it has shown that it can likely reach intercontinental ballistic missile ranges, including putting Alaska at risk.

Kim Jong-un has long expressed his desire for such a test, and to have it on the 4 July holiday in the US is just the icing on his very large cake.

Image copyrightREUTERS

Image captionNorth Korean state TV released photos of the purported ICBM test launch

Despite this technical achievement, however, it is likely many outside North Korea will continue to be sceptical. They will ask for proof of working guidance, re-entry vehicle, and even a nuclear warhead.

From a technical perspective, though, their engines have demonstrated ICBM ranges, and this would be the first of several paths North Korea has to an ICBM with even greater range.

North Korea's missile programme

What is an ICBM?

• A long-range missile usually designed to carry a nuclear warhead
• The minimum range is 5,500km (3,400 miles), although most fly about 10,000km or more
• Pyongyang has previously displayed two types of ICBMs: the KN-08, with a range of 11,500km, and the KN-14, with a range of 10,000km, but before 4 July had not claimed to have flight tested an ICBM. It is not clear what differentiates the Hwasong-14

Are neighbours and nuclear powers concerned?

South Korea's President Moon Jae-in has called on the United Nations Security Council to take steps against North Korea.

But a strong warning came from the country's Director of Operations of the Joint Chiefs of Staff. Cho Han-Gya said "Kim Jong Un's regime will face destruction" if it "ignores our military's warnings and continues provocations".

Japan said "repeated provocations like this are absolutely unacceptable" and Prime Minister Shinzo Abe said his country would "unite strongly" with the US and South Korea to put pressure on Pyongyang.

US President Donald Trump also responded swiftly on Tuesday.

On his Twitter account he made apparent reference to North Korean leader Kim Jong-un, saying: "Does this guy have anything better to do with his life?

"Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense once and for all!"

Image copyrightKCNA/REUTERS

Image captionNorth Korean state TV said the launch was overseen by leader Kim Jong-un

President Trump has repeatedly called on China, Pyongyang's closest economic ally, to pressure North Korea to end its nuclear and missile programmes.

On the prospect of North Korea being able to strike the US, he tweeted in January: "It won't happen." However experts say it might - within five years or less.

Meanwhile, UK Foreign Secretary Boris Johnson said the international community "must redouble its efforts to impose a price on this regime, which strains every nerve and sinew to build nuclear weapons and launch illegal missiles, even as the people of North Korea endure starvation and poverty".

BBC NEWS

Scientists explain ancient Rome's long-lasting concrete

Researchers have unlocked the chemistry of Roman concrete which has resisted the elements for thousands of years.

Ancient sea walls built by the Romans used a concrete made from lime and volcanic ash to bind with rocks.

Now scientists have discovered that elements within the volcanic material reacted with sea water to strengthen the construction.

They believe the discovery could lead to more environmentally friendly building materials.

Unlike the modern concrete mixture which erodes over time, the Roman substance has long puzzled researchers.

Rather than eroding, particularly in the presence of sea water, the material seems to gain strength from the exposure.

In previous tests with samples from ancient Roman sea walls and harbours, researchers learned that the concrete contained a rare mineral called aluminium tobermorite.

They believe that this strengthening substance crystallised in the lime as the Roman mixture generated heat when exposed to sea water.

Researchers have now carried out a more detailed examination of the harbour samples using an electron microscope to map the distribution of elements. They also used two other techniques, X-ray micro-diffraction and Raman spectroscopy, to gain a deeper understanding of the chemistry at play.

This new study says the scientists found significant amounts of tobermorite growing through the fabric of the concrete, with a related, porous mineral called phillipsite.

The researchers say that the long-term exposure to sea water helped these crystals to keep on growing over time, reinforcing the concrete and preventing cracks from developing.

"Contrary to the principles of modern cement-based concrete," said co-author Marie Jackson from the University of Utah, US, "the Romans created a rock-like concrete that thrives in open chemical exchange with seawater."

"It's a very rare occurrence in the Earth."

The ancient mixture differs greatly from the current approach. Modern buildings are constructed with concrete based on Portland cement.

This involves heating and crushing a mixture of several ingredients including limestone, sandstone, ash, chalk, iron and clay. The fine material is then mixed with "aggregates", such as rocks or sand, to build concrete structures.

The process of making cement has a heavy environmental penalty, being responsible for around 5% of global emissions of CO2.

So could the greater understanding of the ancient Roman mixture lead to greener building materials?

Prof Jackson is testing new materials using sea water and volcanic rock from the western United States. Speaking to the BBC earlier this year, she argued that the planned Swansea tidal lagoon should be built using the ancient Roman knowledge of concrete.

"Their technique was based on building very massive structures that are really quite environmentally sustainable and very long-lasting," she said.

"I think Roman concrete or a type of it would be a very good choice [for Swansea]. That project is going to require 120 years of service life to amortise [pay back] the investment.

"We know that Portland cement concretes contain steel reinforcements. Those will surely corrode in at least half of that service lifetime."

There are a number of limiting factors that make the revival of the Roman approach very challenging. One is the lack of suitable volcanic rocks. The Romans, the scientists say, were fortunate that the right materials were on their doorstep.

Another drawback is the lack of the precise mixture that the Romans followed. It might take years of experimenting to discover the full formula.

The research has been published in the journal American Mineralogist.

Follow Matt on Twitter 

BBC NEWS

EU's Juncker calls empty European Parliament 'ridiculous'

European Commission President Jean-Claude Juncker has launched a bitter attack on members of the European Parliament for failing to show up.

Standing up in almost empty chamber in Strasbourg, he denounced the body as "ridiculous, totally ridiculous".

Estimating the number of MEPs at around 30, he said it proved that the parliament was "not serious".

Parliament President Antonio Tajani reacted furiously, accusing him of a lack of respect.

"You can criticise the parliament, but it's not the commission's job to control the parliament, it's the parliament that has to control the commission," he said.

But the clash continued. Mr Juncker, who is in charge of the EU's executive body, angrily rebuked MEPs for failing to attend the session reviewing the six-month presidency of Malta, the bloc's smallest member state.

It was one of the most acrimonious public rows between top EU officials in recent years.

Rows of empty seats - Adam Fleming in Strasbourg writes:

It is rare for the head of one EU institution to take such a public swipe at the legitimacy of another.

But it is true that Strasbourg feels very empty for the final session of the European Parliament before the summer holidays. I counted fewer than 100 people in the chamber this morning - and that included the officials accompanying Mr Juncker and the Maltese prime minister.

"People can't be bothered to turn up," a British MEP told me. "Some have started their seven weeks of paid holiday already," he added.

Or perhaps it is the fact that some debates in this session have been cancelled so that politicians can attend the funeral of Simone Veil - a former president of the parliament - which will be held in France tomorrow?

The parliamentary authorities will be unhappy to have been criticised so publicly by such a high-profile figure as Mr Juncker.

---

Malta's Prime Minister, Joseph Muscat, looked on with a broad grin as the argument unfolded. The debate was due to focus primarily on the EU's struggle to relocate 160,000 refugees from Italy and Greece.

"There are only a few members in the plenary to control the commission. You are ridiculous," Mr Juncker repeated. In total, the parliament has 751 deputies.

• English losing importance in EU - Juncker
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• EU needs stronger defence arm - Juncker

Ignoring a further objection by the parliament president to his choice of language, Mr Juncker told the few MEPs in the chamber: "I will never again attend a meeting of this kind".

Mr Juncker complained that if Germany's Chancellor Angela Merkel or French President Emmanuel Macron had been in the chamber, it would have been full.

The spat overshadowed Mr Muscat's own assessment of the EU's response to the migrant crisis.

Describing the situation as a "fiasco", the Maltese leader called for an honest debate on Europe's values.

The vast majority of the 101,000 migrants entering Europe in 2017 so far have crossed the Mediterranean towards Italy. According to latest figures, 2,247 people have died or are missing at sea.

BBC NEWS

Italy-Austria tension over border troops at Brenner Pass

Italy has summoned Austria's ambassador after the government in Vienna announced it was ready to deploy border troops to block any migrant influx.

Austrian Defence Minister Hans Peter Doskozil told Kronen Zeitung daily that troops could go to the Brenner Pass.

He said four Pandur armoured personnel carriers had been sent to the Tyrol region and 750 troops were on standby.

Austria has border checks with Hungary and Slovenia. But elsewhere it adheres to the EU open borders system.

Mr Doskozil said a military deployment at the busy Alpine pass, on the Italian border, would be "indispensable if the influx into Italy [across the Mediterranean] does not diminish".

Later Italy's foreign ministry said it had summoned Austrian Ambassador Rene Pollitzer "following the Austrian government's statement about deploying troops to the Brenner (pass)".

People-smuggling gangs have been exploiting the violence and chaos in Libya. The shortest crossing from Libya to Italy is only about 460km (290 miles).

• Italy and Austria row over migrant crossing
• Austria tightens controls amid Italian criticism

Italy has warned that the current scale of migrant arrivals is unsustainable and that it could even close its ports and impound aid agencies' rescue ships.

The EU's Schengen system - free movement across most European borders - was overwhelmed by an influx of migrants and refugees in 2015.

They reached Central Europe via the Balkans - and most sought asylum in Germany. Since then, tighter border controls in the Balkans have reduced the numbers heading north from Greece.

Most of the influx to Austria was via Hungary. Many of those who came by train or on foot were refugees from Syria, Iraq and other conflict zones.

The Brenner Pass is now seen as a potential migration hotspot, as the influx to Italy so far this year is higher than last year.

Nearly 85,000 migrants and refugees arrived in Italy in the first half of this year, across the Mediterranean. The UN refugee agency UNHCR says that is about 20% more than in the first half of 2016.

So far 101,000 migrants have entered Europe in 2017 via the Mediterranean and according to the latest figures, 2,247 people have died or are missing at sea.

A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.

BBC NEWS

North Korea hails 'ICBM test' success

North Korea says it has successfully tested its first "intercontinental ballistic missile" (ICBM).

A state television announcement said the missile, which landed in the Sea of Japan on Tuesday, could hit targets anywhere in the world.

But the US and Russia said the missile had a medium range and presented no threat to either country.

North Korea has increased the frequency of its missile tests, in defiance of a ban by the UN Security Council.

China and Russia called on Pyongyang to freeze its missile and nuclear activities.

The announcement on North Korea state television said the Hwasong-14 missile test was overseen by leader Kim Jong-un.

It said the projectile had reached an altitude of 2,802km (1,731 miles) and flew 933km for 39 minutes before hitting a target in the sea.

• Have North Korea's missile tests paid off?
• What can the outside world do?
• How advanced is North Korea's nuclear programme?
• North Korea's missile programme

North Korea, it said, was now "a full-fledged nuclear power that has been possessed of the most powerful inter-continental ballistic rocket capable of hitting any part of the world".

It would enable the country to "put an end to the US nuclear war threat and blackmail" and defend the Korean peninsula, it said.

While Pyongyang appears to have made progress, experts believe North Korea does not have the capability to accurately hit a target with an ICBM, or miniaturise a nuclear warhead that can fit onto such a missile.

Other nuclear powers have also cast doubt on North Korea's assessment, with Russia saying the missile only reached an altitude of 535km and flew about 510km.

What is an ICBM?

• A long-range missile usually designed to carry a nuclear warhead
• The minimum range is 5,500km (3,400 miles), although most fly about 10,000km or more
• Pyongyang has previously displayed two types of ICBMs: the KN-08, with a range of 11,500km, and the KN-14, with a range of 10,000km, but before 4 July had not claimed to have flight tested an ICBM. It is not clear what differentiates the Hwasong-14

How far could this missile travel?

The big question is what range it has, says the BBC's Steven Evans in Seoul. Could it hit the United States?

David Wright, a physicist with the US-based Union of Concerned Scientists, says that if the reports are correct, this missile could "reach a maximum range of roughly 6,700km on a standard trajectory".

That range would allow it to reach Alaska, but not the large islands of Hawaii or the other 48 US states, he says.

It is not just a missile that North Korea would need, our correspondent adds. It must also have the ability to protect a warhead as it re-enters the atmosphere, and it is not clear if North Korea can do that.

What does this test tell us? By defence expert Melissa Hanham

Once again North Korea has defied the odds and thumbed its nose at the world in a single missile launch. With the test of the Hwasong-14, it has shown that it can likely reach intercontinental ballistic missile ranges including putting Alaska at risk.

Kim Jong-un has long expressed his desire for such a test, and to have it on the 4 July holiday in the US is just the icing on his very large cake.

Despite this technical achievement, however, it is likely many outside North Korea will continue to be sceptical of North Korea's missile. They will ask for proof of working guidance, re-entry vehicle, and even a nuclear warhead.

From a technical perspective, though, their engines have demonstrated ICBM ranges, and this would be the first of several paths North Korea has to an ICBM with even greater range.

Are neighbours and nuclear powers concerned?

South Korea's President Moon Jae-in has called on the UN Security Council to take steps against North Korea.

Japan described "repeated provocations like this are absolutely unacceptable" and Prime Minister Shinzo Abe said his country would "unite strongly" with the US and South Korea to put pressure on Pyongyang.

Russia and China said the launch was "unacceptable".

Chinese President Xi Jinping is in Moscow, where he held talks with Russian President Vladimir Putin.

The two leaders urged Pyongyang to suspend all its tests. They also asked the US and South Korea to not hold joint military exercises.

US President Donald Trump also responded swiftly on Tuesday.

On his Twitter account he made apparent reference to North Korean leader Kim Jong-un, saying: "Does this guy have anything better to do with his life?"

"Hard to believe that South Korea and Japan will put up with this much longer. Perhaps China will put a heavy move on North Korea and end this nonsense onc

President Trump has repeatedly called on China, Pyongyang's closest economic ally, to pressure North Korea to end its nuclear and missile programmes.

On the prospect of North Korea being able to strike the US, he tweeted in January: "It won't happen". However experts say it might - within five years or less.

Beijing called for "restraint" following the latest test on Tuesday.

Foreign ministry spokesman Geng Shuang said China was opposed to North Korea going against clear UN Security Council resolutions on its missile launches.

Meanwhile, a spokesman for Prime Minister Theresa May said the UK "stood alongside the US and our allies to confront the threat North Korea poses to international security".

BBC NEWS