The White House on Tuesday said that it would “closely monitor” North Korea amid reports that Pyongyang is increasing activity at a nuclear test site.

“We closely monitor actions such as that,” said White House press secretary Jay Carney aboard Air Force One, en route to Oso, Wash., with President Obama. “North Korea has a history of taking provocative actions, and we are always mindful of the possibility that such an action could be taken.”

South Korea said it had seen signs that the North might be planning a new nuclear test. The reports also come as President Obama is set to begin a four-nation, week-long tour of Asia.

Carney said the U.S. had seen the reports, but declined to say if U.S. intelligence had picked up similar signs.

“I’m not in a position to discuss the information we have and how we evaluate what’s happening in North Korea,” he said. “We’ve certainly seen the public reports and the press reports. And again, I would note that there is a kind of cyclical nature to the provocative actions that North Korea tends to take, and we’ll be watching it very closely.”

Carney sidestepped a question about whether a North Korean nuclear test would change Obama’s travel plans in Asia.

The president will visit Japan, South Korea, Malaysia and the Philippines to bolster trade ties and reassure allies worried about China's growing military and economic strength.

Obama has pushed for U.S. foreign policy to “pivot” to Asia, but that effort has been sidetracked by continued Mideast instability and a standoff with Russia over Ukraine's sovereignty.