SEOUL, Feb. 7 (Xinhua) - Top diplomats of South Korea and the United States held telephone talks on Tuesday to discuss stronger bilateral alliance and the Democratic People's Republic of Korea (DPRK)'s nuclear program, Seoul's foreign ministry said.

South Korean Foreign Minister Yun Byung-se held a 25-minute phone conversation earlier in the morning with his U.S. counterpart, Secretary of State Rex Tillerson who took office a week earlier.

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

The two officials agreed to strengthen the U.S.-South Korea relations to the strongest ever under the Trump administration to effectively tackle the DPRK's nuclear program and other relevant issues.

The South Korean diplomat stressed that the DPRK's nuclear program would become the most serious issue faced by the new U.S. administration, saying the two countries should be prepared for any possible DPRK provocations.

On Jan. 30, U.S. 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. U.S. Defense Secretary James Mattis visited South Korea last week.