Donald Trump has said "all options are on the table" for a US response to North Korea's launch of a missile over Japan.
In a written statement, the US president said the test had "signalled its contempt for its neighbours, for all members of the United Nations, and for minimum standards of acceptable international behaviour".
The news comes as North Korea sparks yet more concerns regarding its nuclear agenda after firing a missile over Japan.
Mr Trump added:
"Threatening and destabilising actions only increase the North Korean regime's isolation in the region and among all nations of the world. All options are on the table."
Mr Trump and Japanese prime minister Shinzo Abe have also reportedly spoken on the telephone about the latest missile test.
The White House said in a statement that North Korea represents "a grave and growing direct threat.”
The statement continued:
"President Trump and prime minister Abe committed to increasing pressure on North Korea, and doing their utmost to convince the international community to do the same."
Whilst Mr Abe said: "Japan's and the US positions are totally at one".
The prime minister added that both nations were in "total agreement" that an emergency meeting was needed at the UN Security Council in order to tackle this “unprecedented threat”.
He also said Mr Trump has expressed his "strong commitment" to defending Japan.
The Inter-Continental Ballistic Missile was fired from the North Korean capital Pyongyang and flew over Japan before plunging into the northern Pacific Ocean.
The test-flight is an aggressive move from North Korea, and sends a clear message of defiance to Japan’s close ally, the US, as they conduct War games in nearby Seoul.
The South's joint chiefs of staff have said that the missile travelled around 1,677 miles as it flew over the Japanese island of Hokkaido.
The launch is the first to cross Japan since 2009 and has heightened concerns that the North will soon possess an arsenal of nuclear weapons capable of targeting the US.
Some analysts believe the North could have viable long-range nuclear missiles before the end of President Donald Trump's first term in 2021.
The move follows threats from North Korea to target the US territory of Guam, which hosts a major military base.
Although this missile did not land near Guam, which is about 1,550 miles south of Tokyo, the range of the missile demonstrates that the North is capable of following through on its threat.
Japan's NHK TV said the missile separated into three parts during its launch, and Prime Minister Shinzo Abe told reporters:
"We will do our utmost to protect people's lives. This reckless act of launching a missile that flies over our country is an unprecedented, serious and important threat."
Foreign secretary Boris Johnson has since criticised the “reckless provocation” that the launch was designed to create.
Mr Johnson said in a tweet:
The launch comes on the eve of Theresa May's planned visit to Japan to discuss Britain's post-Brexit trade.
The Prime Minister, who will be received by Emperor Akihito and Mr Abe, will put trade and investment opportunities at the heart of her visit.
As well as this, defence and security cooperation are expected to be key themes of the trip.