SEOUL, South Korea — President Donald Trump has repeatedly said he’s willing to engage in talks with the North “if conditions are right,” using language also touted by Seoul and Pyongyang.

But the U.S. administration, four months into office, has not spelled out what those conditions may be, and analysts caution that a resumption of long-stalled negotiations over North Korea’s nuclear weapons program is far from imminent.

“I think each party has a different threshold for what must happen for negotiations to resume, and I do not think those thresholds are clear to each party, which makes resuming negotiations exceedingly difficult,” said Catherine Dill of the James Martin Center for Nonproliferation Studies in Monterey, Calif.

For one thing, each side has a diametrically opposed end goal. The United States and its allies want a denuclearized peninsula while Pyongyang is determined to be accepted as a nuclear power.

The bar has been raised as North Korea has shown major progress over the past year and a half with a series of missile tests and five underground nuclear blasts, including two in 2016.

The test launch on Sunday of a ballistic missile was considered one of its most successful yet, with experts saying the flight path showed the warhead could eventually reach as far as Alaska or Hawaii.

That occurred just hours after a North Korean diplomat said her country would hold a dialogue with the United States “under the right conditions.”

Robert Einhorn, an arms control and nonproliferation expert at the Brookings Institution, said the North Koreans can’t have it both ways.

“I don’t think the recent test precludes sitting down, but I don’t believe it’s possible to talk if they continue,” he said in a telephone interview. “I think if North Korea really wants to explore engagement and see what it might mean for them then they will have to show restraint.”

WINDOW OF OPPORTUNITY Past dialogue focused on wringing concessions — including an agreement to shut down nuclear facilities — from the North in exchange for humanitarian assistance and diplomatic rewards.

But the so-called six-party talks involving the United States, China, Russia, Japan and the two Koreas broke down in 2009 after the North launched a satellite shortly after President Barack Obama took office.

Obama, who had initially shown a willingness to engage, shifted to a policy known as “strategic patience” that relied on punishing economic sanctions and diplomatic pressure to curb Pyongyang’s nuclear ambitions.

Trump declared “strategic patience” dead shortly after his inauguration in January, although his recent declaration of a policy of “maximum pressure and engagement” has many similarities with the previous administration.

Analysts say the fact that he hasn’t outlined specific conditions for talks could give him room to maneuver.

Trump administration officials also have signaled they may be willing to reconsider some issues that weren’t up for debate in the past, including a possible de-emphasis on human rights, said Scott Snyder of the New York-based Council on Foreign Relations.

Secretary of State Rex Tillerson also explicitly ruled out a goal of regime change in a U.N. speech last month.

“The Trump administration statements suggest that there could be a plausible strategic security/issue tradeoff that sets aside some of these other issues at this time,” Snyder said, adding such a move would almost certainly be met with a strong backlash on Capitol Hill.

He said talk of persuading the North Koreans to freeze their nuclear program as opposed to dismantling it altogether appears also to be gaining momentum.

“Frankly the conditions for dialogue implied a freeze but it also implied that a freeze was a starting point toward denuclearization,” he said. “The concern is ‘what if the freeze ends up being an end point?’”

China’s growing impatience with its communist ally also may be a positive factor if the parties ever make it back to the table, analysts said.

Beijing has signed onto recent U.N. Security Council sanctions and suspended coal imports from the North, although it also has expressed anger over the deployment of a U.S. missile defense system in South Korea.

“If in fact China is prepared to turn up the pressure against North Korea, then North Korea might see advantage in engaging and demonstrating restraint,” Einhorn said.

SUNSHINE POLICY 2.0? While Trump’s policies remain uncertain, South Korea’s new President Moon Jae-in was elected last week vowing to pursue dialogue and restore trade in hopes of reviving the so-called Sunshine policy of previous liberal governments.

But even the left-leaning leader was sounding more hawkish after Sunday’s missile test, which occurred just five days after his landslide election. He called it a “reckless provocation” and said dialogue would only be possible if “North Korea changes its attitude.”

Trump said Wednesday that he looks forward to working closely with Moon on resolving the North Korean nuclear issue and is willing to engage with Pyongyang “if conditions are right,” South Korean envoy Hong Seok-hyun reportedly said after a 15-minute meeting with the U.S. president.

The two leaders also plan to meet in June.

Meanwhile, the White House has made clear that the current conditions are definitely not right for engagement. Instead the Trump administration has pushed for tougher sanctions and urged China to step up economic pressure on the North.

“Having a missile test is not the way to sit down with the president because he’s absolutely not going to do it,” the U.S. ambassador to the United Nations, Nikki Haley, said after Sunday’s test.

“I can tell you, he can sit there and say all the conditions he wants. Until he meets our conditions, we’re not sitting down with him,” she said when asked on ABC’s “This Week” program about the possibility of a meeting with Kim.

gamel.kim@stripes.com Twitter: @kimgamel