SEOUL – On Friday the United States gave a clear message to North Korea on its escalating nuclear weapons’ programme that pre-emptive military action is an “option on the table”.

During his visit to South Korea, Washington’s top diplomat Rex Tillerson said that the country’s “strategic patience” with N. Korea was over, adding that option was on the table if threats from the rogue regime escalated.

Tillerson’s visit comes after a missile test-fired last week that Pyongyang termed as a drill for an attack on US bases in Japan.

The US has 28,000 troops deployed in South Korea to keep it safe from the North, but the capital Seoul is within range of Pyongyang’s artillery.

Under that policy, the US ruled out engaging the North until it made a tangible commitment to denuclearisation, hoping that internal stresses in the isolated country would bring about change.

“We are exploring a new range of diplomatic, security, economic measures. All options are on the table,” Tillerson told reporters at a joint press conference with his South Korean counterpart Yun Byung-Se.

North Korea has a long-standing ambition to become a nuclear power, saying it needs to be able to defend itself, and conducted its first underground atomic test in 2006, in the teeth of global opposition.