It concerns the airspace within 30 kilometers (about 19 miles) of the base in southern Japan, where Patriot missiles are deployed.
North Korea began to sharpen its threats in February, after the United Nations reacted to the country's third nuclear test with tougher sanctions. Annual military exercises involving U.S. and South Korean troops have added to the tensions.
At the Thursday House Intelligence Committee hearing, Clapper said the United States believed the primary objective of Kim's bellicose rhetoric was to "consolidate and affirm his power."
Earlier in the crisis, the United States drew attention to shows of strength, such as practice missions by B-2 stealth bombers.
Kerry said Friday that U.S. officials were working to calm the crisis, noting President Barack Obama had canceled some of the exercises.
"I think we have lowered our rhetoric significantly," Kerry said.