The US military has picked up indications that North Korea is prepping for a new missile test, potentially of an intercontinental ballistic missile, a US defense official said Tuesday.

Speaking on condition of anonymity, the official told AFP that if the test goes ahead, it would "probably" occur on July 27, which is the anniversary date of the signing of the Korean Armistice Agreement.

"They're setting up for something," a second defense official said.

The first official said the test would be of either an intermediate-range missile or North Korea's ICBM -- known as a KN-20 or a Hwasong-14.

Pyongyang triggered global alarm on July 4 -- Independence Day in America -- when it test-fired its first ICBM which experts believe can reach Alaska.