Mike Pence warns North Korea:Don't test Donald Trump's resolve

Seoul : US Vice President Mike Pence on Monday warned North Korea against testing America's mettle with its sabre-rattling, saying Washington will defeat any use of military force with an "overwhelming and effective" response.

During a press conference with South Korea's Acting President and Prime Minister Hwang Kyo-ahn, Pence also reassured South Korea that Washington's security commitment to its Asian ally is "ironclad and immutable".

"North Korea will do well not to test his (Trump's) resolve or strength of the armed forces of the US in this region," Pence said, noting the US President's recent decision on military action in Syria and Afghanistan.

"We hope to achieve this objective (Pyongyang's denuclearisation) through peaceful means, but all options are on the table," he added.

Pence said that his country's "era of strategic patience" with North Korea is over and warned Pyongyang not to test the resolve of the US, Yonhap news agency reported.

Calling the North the region's "most dangerous and urgent threat", Pence denounced its failure to follow through on its denuclearisation commitments.

"North Korea answered our overtures (for denuclearization) with willful deception, broken promises, and nuclear and missile tests," he said.

In Moscow, Russian Foreign Minister Sergey Lavrov said he expects Washington to refrain from taking unilateral steps towards North Korea, Russia's Tass news agency reported.

"If the US Vice President meant that Washington could unilaterally use military force, then it is a risky road," Lavrov said, referring to Pence's comment that the "era of strategic patience is over".

Lavrov also said North Korea's adventurous missile launches are unacceptable as they are a violation of the UN Security Council's resolutions.

"But that does not mean that others can violate international law in response and use military force," he said, according to Tass.

Pence began his three-day visit to South Korea -- the first leg of his four-nation tour of the Asia-Pacific region -- on Sunday afternoon, hours after North Korea botched an attempt to launch yet another ballistic missile.

On Monday, the US and South Korea launched a joint air force military exercise to ensure readiness against North Korea, according to the South Korean media.

Earlier in the day, Pence visited the Korean demilitarised zone (DMZ), which he described as the "frontier of freedom", according to the report.

The DMZ is the highly-fortified de facto border between North and South Korea.

South Korea's acting President Hwang Kyo-ahn hailed the early deployment of the controversial US missile defence system (known as THAAD) designed to protect against threats from North Korea.

Pence said he was disappointed that China had taken retaliatory actions against South Korea in response to the move.

Pence said on Monday that Trump was "very hopeful that China will take actions to bring about a change of policy in North Korea. An abandonment of its nuclear weapons programme and its ballistic missile programme."

The US Vice President will leave for Japan on Tuesday. His trip includes visits to Indonesia and Australia.