The top U.S. military commander in the Pacific warned the situation in North Korea is a "recipe for disaster," as the region prepares for U.S. President Donald Trump's first visit to the region.

Adm. Harry Harris, head of the U.S. Pacific Command, said in a speech Tuesday in Singapore that China must do more to pressure its neighbor and ally over its weapons programs. The U.S. government will continue to be presented with military options for dealing with Kim Jong Un, he said, although he added a diplomatic solution remains the priority.

"Combining nuclear warheads with ballistic missiles in the hands of a volatile leader, Kim Jong Un, is a recipe for disaster," Harris said. "Many people have thought about military options being unimaginable regarding North Korea. Folks, I must imagine the unimagined."