Increasingly bellicose rhetoric has come from Pyongyang and its leader, with North Korea urging foreign companies and tourists to leave South Korea and warning that the countries are on the verge of a nuclear war.
At the White House, spokesman Jay Carney brushed off the North's declaration that nuclear war was imminent as "more unhelpful rhetoric" and part of a pattern of combative statements and behavior that Pyongyang's leadership has demonstrated for years. He said the U.S. was working with Seoul and Tokyo on the issue.
"It is unhelpful, it is concerning, it is provocative," Carney said.
Senate Armed Services Committee Chairman Carl Levin, D-Mich., told Locklear that the North Korean government's threats "appear to exceed its capabilities, and its use of what capabilities it has against the U.S. or our allies seems highly unlikely and would be completely contrary to the regime's primary goal of survival."
"Nonetheless, its words and actions are not without consequences," Levin said.
The Democrat questioned the Obama administration's decision to delay a long-scheduled operational test of an intercontinental ballistic missile amid the North Korea rhetoric.
Locklear said he agreed with the decision to delay the test.
"We have demonstrated to the people of the region, demonstrated to the leadership of North Korea, our ability and willingness to defend our nation, our people, our allies and our forward deployed forces," Locklear said, citing other steps the U.S. military has taken in recent weeks.
The U.S. has moved two of the Navy's missile-defense ships closer to the Korean peninsula, and a land-based system is being deployed to the Pacific territory of Guam. The U.S. also called attention to the annual U.S.-South Korean military exercise that included a practice run over South Korea by B-2 stealth bombers.