SEOUL • Top diplomats of South Korea and the United States have held telephone conversations to discuss a stronger bilateral alliance and North Korea's nuclear programme.

Seoul's Foreign Ministry said yesterday that South Korean Foreign Minister Yun Byung Se held a 25-minute phone conversation earlier in the morning with his US counterpart, Secretary of State Rex Tillerson, who took office a week ago.

Citing a series of senior-level phone calls between the two allies, Mr Yun highly appreciated the importance the Trump administration placed on the bilateral alliance.

The two officials agreed to strengthen US-South Korea relations to the strongest ever under the Trump administration to effectively tackle North Korea's nuclear programme and other relevant issues.

The South Korean diplomat stressed that North Korea's nuclear programme would become the most serious issue faced by the new US administration, saying the two countries should be prepared for any possible provocation from North Korea.

On Jan 30, US President Donald Trump held phone talks with South Korean Prime Minister Hwang Kyo Ahn who is serving as acting president following the impeachment of President Park Geun Hye.

US Defence Secretary James Mattis visited South Korea last week. He said last Friday that any nuclear attack by North Korea would trigger an "effective and overwhelming" response, as he sought to reassure Asian allies rattled by Mr Trump's isolationist rhetoric.

South Korea and Japan had been worried that Mr Trump might follow through on threats to cut back on US military support to them. South Korea is working with the US to install the Terminal High Altitude Area Defence system to guard against missiles from the North.

Mr Mattis reassured Seoul last week that the US remains committed to the project.

XINHUA, AGENCE FRANCE-PRESSE, REUTERS