A top U.S. Air Force general on Tuesday said he expects North Korea's "Christmas gift" to the United States to be a long-range missile test, after Pyongyang delivered an ominous threat ahead of a unilateral year-end deadline for progress in nuclear talks.

"What I would expect is some type of long-range ballistic missile would be the gift," said Gen. Charles Brown, commander of the U.S. Pacific Air Forces. "It's just a matter of does it come on Christmas Eve, does it come on Christmas Day, does it come after the New Year."

Brown made the remarks to U.S. media at a roundtable discussion in Washington.