WASHINGTON -- U.S. Secretary of State Rex Tillerson's surprising diplomatic offer of unconditional talks with North Korea hinges on two big X factors: Does the North even want talks, and is U.S. President Donald Trump fully behind his top diplomat?

The early signs were not promising. The White House on Wednesday contradicted Tillerson's overture. North Korea has yet to respond.

The diplomatic initiative, made in remarks at a Washington think-tank , came two weeks after North Korea tested a missile that could potentially carry a nuclear warhead to the U.S. Eastern Seaboard. That's a capability the North has strove for decades to master. Trump has vowed to stop it from reaching its goal, using military force if necessary.

His administration has pursued a policy of "maximum pressure and engagement" -- with the overwhelming emphasis on pressuring Kim Jong Un's authoritarian government through economic restrictions and diplomatic isolation to compel it to negotiate away its nukes. Tillerson, who will address a U.N. Security Council meeting on North Korea on Friday, has carried the torch for engagement, and as fears of confrontation have risen, has progressively eased the threshold under which he says the U.S. could hold direct discussions with the reclusive nation.

In March, he said North Korea first had to give up its nuclear weapons. A month later he demanded "concrete steps" reducing its threat. Tillerson said this summer talks could happen after the North stopped missile tests. And on Tuesday, for the first time, he explicitly dropped the condition that North Korea at least agree that the goal of any conversations be the elimination of its nuclear arsenal.

"We are ready to talk anytime North Korea would like to talk. And we are ready to have the first meeting without preconditions," Tillerson said at the Atlantic Council, adding that the North would need to pause its weapons testing. It has conducted more than 20 ballistic missile launches and one nuclear test explosion this year.

He called it "unrealistic" to expect it to enter talks ready to relinquish a WMD program it invested so much in developing, although that remained the ultimate goal.

On Wednesday, the White House conflicted with Tillerson's offer of talks without preconditions. A National Security Council spokesperson said that North Korea must not only first refrain from provocations but take "sincere and meaningful actions toward denuclearization." The spokesperson, who was not authorized to be quoted by name and requested anonymity, said that given North Korea's most recent missile test, now was not the time for talks.

Late Wednesday, State Department spokeswoman Heather Nauert echoed that in a tweet: "We remain open to dialogue when North Korea is willing to conduct a serious & credible dialogue on the peaceful denuclearization, but that time is not now."

There's ample precedent for a public disconnect between Tillerson and Trump on vital issues of foreign policy. In October, Trump appeared to undercut Tillerson by saying the top diplomat was "wasting his time" trying to negotiate with North Korea. Trump's tweet followed Tillerson's talk about Washington maintaining back-channel communications with Pyongyang.

And doubts about Trump's broader confidence in Tillerson have persisted since White House officials revealed a plan last month to replace Tillerson with CIA Director Mike Pompeo.

China, which has urged dialogue with North Korea, and U.S. ally South Korea, which fears disruption to the Winter Olympics it hosts in February, both welcomed Tillerson's proposal.

But without White House support, Tillerson's call for unconditional talks would fall flat, said Mark Fitzpatrick at the International Institute for Strategic Studies. "A skeptic might say that at least he wants to show the U.S. is trying diplomacy, so as to make any future military action more justifiable," Fitzpatrick said.

Patrick Cronin, an Asia expert at the Center for a New American Security think-tank , said the Trump administration "has played hardball in trying to convert pressure into diplomatic opportunity." But so far, North Korea hasn't been willing to engage. He said it's unclear if the North will want to negotiate as it nears deployment of a nuclear missile that could strike America.

Last week, U.N. political chief Jeffrey Feltman made a rare visit to North Korea and met the foreign minister - a member of the powerful Politburo. Feltman, a former U.S. diplomat, said senior North Korean officials told him "it was important to prevent war." He said he urged them to "start talking about talks," a commitment he didn't get.

After a closed briefing by Feltman on Tuesday, Sweden's deputy U.N. ambassador, Carl Skau, was supportive but skeptical about chances for an opening. "There's nothing that was said that left us less worried than we were before," Skau told The Associated Press.

Associated Press writer Edith M. Lederer at the United Nations contributed to this report.