U.S. National Security Adviser Robert O'Brien on Tuesday called on North Korea to refrain from provocations and return to dialogue, saying the door for dialogue remains open.

O'Brien made the call during a virtual seminar hosted by the Center for the National Interest, a U.S. think tank in Washington.

In the seminar marking the 70th anniversary of the start of the Korean War, O'Brien said U.S. President Donald Trump is committed to "enduring peace" on the Korean Peninsula and that the U.S. wants to see North Korea achieve a "bright economic future" under leader Kim Jong-un.

The security adviser then said that tangible progress has been slow, but the door for dialogue and progress remains open.

O'Brien continued that the U.S. is committed to engagement, and to achieving the goals set forth at the Singapore Summit, referring to the first summit between Trump and Kim in June 2018.

He said Washington continues to call on North Korea to avoid provocations, abide by obligations under U.N. Security Council resolutions and return to sustained and substantive negotiations.