South Korean media said leader Kim Jong-un may be preparing to test a new, upgraded prototype of an intercontinental ballistic missile as early as today.
However US officials, speaking anonymously, cautioned that they did not have such precise information about the range or potential timing of Pyongyang's missile test, should it happen.
One official suggested Pyongyang could be largely seeking to provoke the Trump administration.
One intelligence official told Reuters: "If they do something, it would more likely be a test of Trump than a test of a delivery system.
"They probably want to see how he reacts to a provocation, even a minor one, and if they really want to poke him, they'll do it right away."
In his New Year's speech, leader Kim said North Korea was close to test launching an ICBM, and state media has said a launch could come at any time.