The Secretary of State REX TILLERSON warned that the White House would soon have to decide whether to impose secondary sanctions on such nations.
TILLERSON said the Trump Administration has sought to increase pressure on North Korea over its nuclear and missile activities.
He was speaking at a hearing by the US Senate Foreign Relations Committee.
TILLERSON said the North Korea issue would be discussed with China, which is Pyongyang’s major ally, at high-level talks next week.
North Korea is believed to be making progress toward developing a ballistic missile capable of reaching the US.
Recent missile tests by Pyongyang in defiance of a ban by the United Nations, sparked international alarm.