Obama national security adviser Susan Rice said Thursday that the U.S. has consistently failed to curtail North Korea's nuclear ambitions, even during the Obama era.

"You can call it a failure," Rice told CNN. "I accept that characterization of the efforts of the United States over the last two decades."

Rice, who served as the U.S. ambassador to the United Nations for eight years before transitioning to the role of national security adviser, said the Democratic People's Republic of Korea has now vexed four successive American administrations, both Democrat and Republican. She said each administration has tried a range of measures, from sanctions and pressure, cooperation with China, and "other methods that we shouldn't speak about on television," to no avail.

"The fact of the matter is, that despite all of those efforts, the North Korean regime has been able to succeed in progressing with its program, both nuclear and missile," Rice said. "That's a very unfortunate outcome. But we are where we are. And we now need to decide how to proceed."

Rice advocated in a Thursday morning opinion piece in the New York Times that President Trump should tamp down his rhetoric and learn to live with a nuclear North Korea.

"History shows that we can, if we must, tolerate nuclear weapons in North Korea — the same way we tolerated the far greater threat of thousands of Soviet nuclear weapons during the Cold War," she wrote. "It will require being pragmatic."

Trump has retweeted views on Twitter that argue former President Barack Obama is to blame for the current escalated tensions with Kim Jong-Un and the perception that the U.S. is vulnerable to a nuclear attack.