Defense Secretary James Mattis said Thursday the military is "ready" to counter the threat from North Korea.

"My responsibility is to have military options if needed," Mattis told reporters in Mountain View, California, where he was visiting a new Defense Department arm designed to speed the integration of new technologies into the U.S. military. "We are ready."

The visit came amid rising tensions over a series of North Korean missile tests that prompted President Donald Trump to threaten the Asian nation with "fire and fury."

When asked what options the U.S. has ready, Mattis declined to answer, saying instead, "I'm not going to tell the enemy what we're going to do."

Mattis said the U.S. effort to counter the nuclear missile ambitions of North Korean leader Kim Jong Un is being "diplomatically led."

Mattis praised the efforts of Ambassador Nikki Haley that resulted in a U.N. Security Council resolution condemning North Korea's actions.

The unanimous vote "didn't just happen by accident," Mattis said. The U.S. is "dealing with the threat with an effective diplomatic effort," he said.