The United States has reiterated its commitment to South Korea, promising "overwhelming response" if the country is faced with an attack from its neighbour, North Korea. During a Washington meeting on 19 October, between US' Secretary of State John Kerry, Secretary of Defence Ash Carter and South Korea's Foreign Minister Yun Byung-se and Defence Minister Han Min-goo, the two countries agreed to improve military and diplomatic efforts to counter nuclear threats from North Korea.

"The US commitment to the defence of South Korea is unwavering," said Carter. "This includes our commitment to provide extended deterrence, guaranteed by the full spectrum of US defence capabilities.

"Make no mistake, any attack on America or our allies will not only be defeated, but any use of nuclear weapons will be met with an overwhelming and effective response," he added.

The allies have agreed to set up a high-level Extended Deterrence Strategy and Consultation Group to leverage "the full breadth of national power – including diplomacy, information, military coordination, and economic elements" in preparation for an attack from North Korea.

The US also announced that the Terminal High Altitude Area Defense (THAAD) missile system will be deployed in South Korea "as soon as possible" despite strong protests from both North Korea and China.

"We do not, and we will not, accept North Korea as a nuclear-armed state," Kerry stressed, during the press conference following the meeting.

"There should be no question in anyone's mind that the alliance with the Republic of South Korea will remain as it has been for decades, which is cornerstone of peace and security in the Asia-Pacific," he added.

While offering assurances that military action would be the last resort against North Korea, the secretary of state warned the use of the "US nuclear umbrella" if required.

Discussing the importance of stronger military presence in South Korea, Yun said that North Korea was nearing the "final stage of nuclear weaponisation".

"What is most important is to continuously demonstrate our capability and deterrence with our commitment and actions so that Pyongyang can feel the panic under their skins," he told reporters.

A few hours after the meeting between the two countries, US Strategic Command and the South Korea Joint Chiefs of Staff confirmed that North Korea attempted another missile launch which failed.