"North Korea's proliferation of weapons systems, including potentially missile technologies or nuclear technologies, very much concerns me," Adm. Samuel Locklear III said in response to a question from U.S. Sen. Richard Blumental, D-Conn., during his appearance.
"We know that over the period of time that North Korea goes through cycles of provocation, one of the things they rely on to fund their ability to do what they do is through -- through proliferation and movement of arms sales around the world."
Locklear said the United States currently has the capacity to intercept any North Korean missile aimed at the U.S. mainland, Alaska, Hawaii, Guam or any of its allies. But he told Sen. John McCain, R-Ariz., missiles should not be intercepted until the target is certain.
In most cases, the United States will already know a missile's target, Locklear said.
"If we don't, it doesn't take long for us to determine where it's going and where it's going to land," he said.
Locklear acknowledged North Korea could also cause "horrendous casualties" in South Korea with artillery already in place on the zone between the two countries.
Locklear has been head of U.S. Pacific Command since March 2012. Gen. James Thurman, commander of U.S. Forces Korea, was unable to testify at the hearing because of the tense situation on the Korean peninsula.