Washington has reportedly told Pyongyang it wants to restart bilateral negotiations.

U.S. National Security Adviser Robert O’Brien made the revelation in an interview published Sunday by the U.S. news website Axios.

O'Brien said that the U.S. told North Korea it would like to continue the negotiations last held in Stockholm in October last year.

He said that the U.S. has been letting the North know through various channels that it would like to get those negotiations “back on track.”

The White House official said that the U.S. hopes North Korean leader Kim Jong-un will follow through with his commitment to denuclearize the Korean Peninsula.

O'Brien added that it was an encouraging sign that the North didn’t make good on its threat to send a "Christmas gift" last month, but added that it does not mean there won't be "some sort of test" in the future.

Some media outlets have suggested it is possible that U.S. President Donald Trump expressed the intent to resume negotiations with the North in a birthday message to Kim last week.

Chung Eui-yong, Seoul's top security adviser who returned last Friday from a three-day U.S. trip, said that Trump asked President Moon Jae-in to relay his birthday message to Kim and that Seoul did so through a “proper” channel.

North Korea said Saturday that it received a message from Trump but did not offer further details.