The president said stronger ties with South Korea and Japan are working, but did not address whether President-elect Donald J. Trump would continue his approach when he takes office in January.

South Korean President Yoon Suk Yeol told Chinese President Xi Jinping that their two countries should cooperate for peace in the face of North Korea and Russia's military cooperation, Yoon's office said on Saturday.

President Yoon Suk Yeol expressed hope Friday for South Korea and China to work together to promote regional peace and stability in response to growing military cooperation between North Korea and Russia as he met with Chinese President Xi Jinping on the margins of a multilateral summit in

The recently signed mutual defense treaty could be used to justify thewidening of the war in Ukraine, as the U.S. says North Korean and Russian troops are already battling Ukrainian forces.

There are two likely possibilities: one, that a North Korean artillery unit is deploying to the front line in western Russia or Ukraine; two, that a Russian unit will operate the tracked, four-person howitzers,