WASHINGTON, March 6 (Xinhua) -- U.S. President Donald Trump on Monday spoke separately over phone with leaders of Japan and South Korea to discuss the latest test-launch of ballistic missiles by the Democratic People's Republic of Korea (DPRK), according to the White House.

Trump emphasized U.S. commitment to stand with Japan and South Korea in the face of the "serious threat" posed by the DPRK, said a statement by the White House.

The Trump administration is taking steps to further enhance the ability to deter and defend against the DPRK's ballistic missiles using the full range of U.S. military capabilities, said the statement.

The phone talks followed the DPRK's test-launch on Monday of four ballistic missiles that flew around 1,000 km toward its eastern waters. Among the four, three reportedly fell into Japan's exclusive economic zone.

The latest missile launch by the DPRK came as the United States and South Korea were conducting their joint military drill.

The Chinese Foreign Ministry said on Monday it is opposed to the launch activities of the DPRK that was in violation of the relevant UN Security Council resolutions, and urged all sides to keep restraint.

Citing the ongoing training exercise jointly conducted by the United States and South Korea, Chinese Foreign Ministry spokesperson Geng Shuang said that under the current circumstances, all relevant parties should keep restraint and avoid provoking each other and intensifying the tense situation in the region.

South Korea and the United States on Wednesday kicked off their joint springtime war game which would mobilize the massive U.S. strategic assets, the Yonhap news agency reported.

The Foal Eagle field training exercise is scheduled to last until late April, bringing USS Carl Vinson aircraft carrier, F-35B stealth fighter jets, B-1B strategic bombers, nuclear-capable B-52 long-range bombers and other strategic assets to the Korean Peninsula.

The DPRK had denounced it as a rehearsal for northward invasion.