Kevin Kim, U.S. chargé d’affaires ad interim, said on Thursday that South Korea’s decision to acquire nuclear-powered submarines reflects evolving regional security challenges.

Kim told a Korea–U.S. parliamentary forum in Seoul that stability underpins the two nations’ shared prosperity.

“Look no further than what has happened in the Yellow Sea recently,” he said in apparent reference to China’s recent activities in the area.

Kim added that this was why U.S. President Donald Trump and President Lee Jae Myung had agreed to boost defense spending and introduce new capabilities such as nuclear submarines.

He called South Korea a “model ally” for investing in its own defense and supporting the presence of U.S. troops.

Kim also hailed the joint fact sheet released after the summit as proof that the alliance now spans every sector.