North Korea’s return to missile testing after a long hiatus raises the stakes for President Trump ahead of planned nuclear negotiations, undermining his claim that his personal relationship with dictator Kim Jong Un has reduced the threat from North Korea and made Asian allies safer.

North Korea says its testing is a warning to South Korea, which is resuming joint military exercises with the United States in August and is also acquiring American F-35 stealth fighter jets. The challenge from Kim to Trump is also clear and appears aimed at squeezing concessions from the U.S. leader when negotiators meet after months of delay. That session is expected soon, Secretary of State Mike Pompeo said this week.

The White House has had a muted response to the short-range ballistic missile tests conducted over the past week, including what the South Korean military described as the firing of “unidentified short-range projectiles” early Friday morning local time. Trump argued that they do not break a pledge Kim made to him that he would not test intercontinental ballistic missiles.

“These are short-range missiles. We never discussed that. We discussed nuclear,” Trump told reporters Thursday as he left the White House for a rally in Cincinnati. He added that “a lot of other countries” test those missiles. Asked if he could still negotiate with Kim, Trump said: “Sure.”

White House officials have also sought to tamp down the importance of the tests while arguing that Trump has made progress in his talks with Kim even if as they appear stalled.

“I think that the president taking this really unusual step of meeting Kim Jong Un at the demilitarized zone on June the 30th, walking into North Korea, has once again opened the door for North Korea to make a strategic decision to give up nuclear weapons and walk through it, into a different future,” national security adviser John Bolton said in an interview with Fox Business on Wednesday.

He added a note of caution, reflecting his long-standing skepticism about diplomacy with Pyongyang. “You have to ask if, when, the real diplomacy is going to begin, when the working-level discussions on denuclearization will begin,” Bolton said.

Ballistic missile launches violate United Nations sanctions on North Korea, and have been cited by the United States as a predicate for sanctions and condemnation.

Until the tests conducted over the past week, Trump had regularly touted a lull of more than 18 months without a North Korean nuclear or long-range missile test as a chief achievement of his un­or­tho­dox outreach to Kim. The recent launches were short-range weapons, not the more worrisome long-range weapons that could potentially deliver nuclear warheads to U.S. shores.

“My relationship with Kim Jong Un is a very good one, as I’m sure you’ve seen,” Trump said Tuesday. “We’ll see what happens. I can’t tell you what’s going to happen. I know one thing: that if my opponent was president — if she won — you would be in a major war right now with North Korea. And we are nowhere close. So we’ll see.”

That was a reference to 2016 Democratic nominee Hillary Clinton, who took the same hard line against North Korean nuclear expansion that Trump did in his first year in office. Trump pivoted last year to a policy of direct engagement with Kim, with a goal of persuading the North Korean leader that he is better off economically and politically without nuclear weapons.

“I have a good relationship with him. I like him; he likes me,” Trump said Tuesday. “We’ll see what happens.”

The shorter-range weapons are a threat to U.S. allies South Korea and Japan, or potentially to U.S. forces in the region.

“North Korea’s consecutive missile launches do not help alleviate tensions on the Korean Peninsula, and we urge them to cease such actions,” South Korea’s Joint Chiefs of Staff said in a statement Wednesday.

Kim supervised Wednesday’s launch of what North Korea called a “newly developed large-caliber multiple launch guided rocket system,” the Korean Central News Agency reported.

The rocket will play a “main role in ground military operations” and was part of the modernization of North Korea’s artillery, KCNA reported.

While South Korea does not want a return to the 2017 bellicose standoff between Trump and Kim, when each threatened the other with military force, South Korean President Moon Jae-in also wants assurances that Trump takes threats against Seoul seriously, analysts said.

North Korea has also threatened to pull out of denuclearization talks with the United States over the planned joint military exercises. Pyongyang claims the exercises would break a promise made by Trump to Kim when the two leaders met at the demilitarized zone between the two Koreas at the end of June.

“This new test of missiles or ‘projectiles’ by Pyongyang is a message to Washington and Seoul: stop joint exercises or we will continue to show off our own offensive military capabilities and raise tensions to a slow boil over time,” Harry Kazianis, a security analyst at the Center for the National Interest, wrote on Twitter.

Kim’s calculation may be that the tests unnerve and weaken both the United States and South Korea, but that Trump would not retaliate by canceling talks or taking other actions so long as Kim does not directly confront or insult him.

It’s a risky strategy, despite Trump’s heavy investment in North Korea, the global hotspot on which he has spent the most time and public capital. Trump has held two summits and one less-formal meeting with Kim that yielded no firm plan or timetable to get rid of North Korea’s nuclear arsenal. The two leaders have exchanged flattering letters, the latest in the past few weeks, diplomats said.

“Trump gave them a pass on short-range ballistic missiles, so they’re clearly taking advantage of this time to perfect these weapons that threaten South Korea and Americans living here,” said Duyeon Kim, a Korea expert at the Center for a New American Security.

The North Korean leader had said in April that he would strengthen his military capabilities, Duyeon Kim said.

“Pyongyang is avoiding provoking the U.S. to keep the dialogue door open by engaging in gray-zone provocations to strengthen its missiles while protesting the upcoming U.S.-South Korea military drills. But short-range ballistic missile tests are still a violation of U.N. Security Council resolutions and last year’s inter-Korean military agreement.”

Trump hosted the leader of Mongolia at the White House on Wednesday, and Bolton visited the country in June, as Trump met with Kim. Mongolia has been mentioned as a potential site for another Trump-Kim summit, although a senior administration official, who spoke on the condition of anonymity to brief reporters on the leader’s visit, said Tuesday that “there’s nothing currently being planned.”

Pompeo is attending an Asian security conference this week in Bangkok, which North Korea is pointedly skipping. North Korea, ostracized and heavily sanctioned by much of the globe, had previously used the annual gathering as a rare opportunity for international exposure and legitimacy.

Pompeo told reporters traveling with him that he anticipates that direct talks between U.S. and North Korean negotiators will take place “before too long.” He also said he will meet with his Japanese and South Korean counterparts in Bangkok.

“I’m very hopeful. Chairman Kim had said when the two leaders met at the DMZ that it could get started in a few weeks. It’s taken a little bit longer than that. There’s been a little bit of preliminary work to be done,” Pompeo said.

Min Joo Kim and Simon Denyer in Seoul and John Hudson in Washington contributed to this report.