U.S. Assistant Secretary of State for East Asia David Stilwell has warned North Korea against taking any "ill-advised" actions amid rising concerns about possible nuclear or long-range missile provocations by the regime.

Stilwell made the remark after a speech at the Center for Strategic and International Studies, a Washington think tank, when asked about a possible North Korean intercontinental ballistic missile test and UN sanctions.

The top U.S. diplomat for East Asia said that President Donald Trump wants to work with North Korea and help build their country, but added the U.S. can't have any more of this "unfortunate ill-advised behavior."

Asked how the U.S. would act if China and Russia disapprove of sanctions against Pyongyang, Stilwell said that a nuclear North Korea is not something anybody really wants and a long list of UN Security Council resolutions supports that.