The Trump administration has “reached out to the North Koreans” to ask them to resume diplomacy since the two sides broke off talks last October, White House national security adviser Robert O’Brien told Axios Sunday.

"We've reached out to the North Koreans and let them know that we would like to continue the negotiations in Stockholm that were last undertaken in early October,” he told the news service.

"We've been letting them know, through various channels, that we would like to get those [negotiations] back on track and to implement Chairman Kim's commitment to denuclearization of the Korean Peninsula,” O’Brien added.

NORTH KOREA SAYS TRUMP BIRTHDAY GREETING NOT ENOUGH TO RESTART TALKS

O’Brien expressed cautious optimism North Korea’s leader Kim Jong-un hasn't yet delivered his promised "Christmas gift" — something many analysts expected would be a nuclear weapons test, Axios reported.

President Trump is hoping to build on inroads he’s made to restart the talks and reach an agreement with the North, the report said. Trump recently sent a birthday message to Kim, but the North Koreans have already said Trump's courtship will not change their policy.

To date, Trump's diplomacy has yielded little results besides giving Kim more time to expand his nuclear arsenal, according to analysts tracking North Korea's supply of nuclear warheads.

US President Donald Trump(L)speaks next to new national security advisor Robert O'Brien on September 18, 2019 at Los Angeles International Airport in Los Angeles, California. (Photo by Nicholas Kamm / AFP via Getty Images)

John Bolton, O'Brien's predecessor as national security adviser, recently told Axios the administration is bluffing about stopping North Korea's nuclear ambitions and should prepare to make a public admission its policy failed badly.

O'Brien said he remains hopeful about Kim's decision — so far — to refrain from launching a nuclear test during the Christmas and New Year timeframe.

CLICK HERE TO GET THE FOX NEWS APP

Kim "promised to send a Christmas present. The president suggested he send him a vase. We didn't get a vase or any other sort of Christmas gift. That appears to be positive," O’Brien told Axios.

"All we know is we were told we were going to get a Christmas gift and the Christmas gift didn't come. And so I think that was an encouraging sign. But, again, that doesn't mean we won't see some sort of test in the future," O'Brien added.