The White House said Monday that the U.S. will continue to apply pressure to North Korea to relinquish its nuclear weapons and ballistic missiles, just days after President Donald Trump said he would no longer use the term “maximum pressure” as the two sides prepare for a historic June 12 meeting between Trump and the North’s Kim Jong Un.

“As the president stated, we have sanctions on. They’re very powerful, and we would not take those sanctions off unless North Korea denuclearized,” White House press secretary Sarah Huckabee Sanders said, in an apparent effort to ease concerns in Tokyo and among other U.S. allies that Trump’s remarks could weaken U.S. and United Nations sanctions on the nuclear-armed North.

“Our policy hasn’t changed,” she said. “Our focus will continue to be on denuclearization.”

Sanders also announced that the June 12 summit in Singapore — the first between a sitting American president and a North Korean leader — will begin at 9 a.m. in the city-state. Other details of the summit remain unclear.

Trump said last Friday that he did not want to continue using the term “maximum pressure” since the two sides were now “getting along.” His remarks came after a meeting with Kim Jong Un’s right-hand man, former North Korean spy chief Kim Yong Chol, at the White House.

Sanders said Trump and his team were “actively preparing” for the summit.

“The advance team in Singapore is finalizing logistical preparations and will remain in place until the summit begins,” she said.

“In the DMZ, the U.S. ambassador’s delegation continues diplomatic negotiations with the North Korean delegation,” she said, referring to talks at the Demilitarized Zone between the two Koreas led by Sung Kim, a former U.S. ambassador to South Korea and former nuclear negotiator with the North, who has been called in from his posting as envoy to the Philippines to lead the preparations.

“Discussions have been very positive, and significant progress has been made,” Sanders added.

Asked about the contents of a letter from Kim Jong Un to Trump that the U.S. leader received during Friday’s meeting, Sanders was mum.

“I’m not going to get into the specifics of the letter,” she said. “But as the president said, they were interesting, and we feel like things are continuing to move forward and good progress has been made.”

In recent weeks, the U.S. president said he was canceling the meeting over the North’s “tremendous anger and open hostility,” only to reverse course days later.

Trump’s sudden shifts in his ongoing diplomatic detente with North Korea has left Japan feeling whiplash as it struggles to recalibrate its own policy with the mercurial U.S. leader’s seemingly on-the-fly game plan.

Prime Minister Shinzo Abe is traveling to Washington on Thursday to meet Trump in a bid to get a better grasp on his approach to the North and to push for a joint way of dealing with Pyongyang.

The Japanese leader had cultivated a close relationship with Trump only to see Tokyo marginalized in recent months after the president accepted an invitation from Kim Jong Un to meet. Abe had been one the strongest backers of the U.S.-led maximum pressure campaign and had worked with Washington in calling for the complete, verifiable, and irreversible dismantlement (CVID) of the North’s nuclear and ballistic missile programs.

Also Monday, a group of seven leading U.S. Senate Democrats, including Senate Minority Leader Chuck Schumer, struck a surprisingly hard-line tone in a letter sent to Trump. The letter urges him to seek CVID of not only the North’s nuclear arsenal, but also the elimination of its chemical and biological weapons cache and its uranium and plutonium enrichment process before any sanctions relief.

Under the maximum pressure campaign, the United States has heaped some of the most stringent sanctions ever on the Kim regime. Trump has boasted that these sanctions were key to bringing the North to the negotiating table, though it is unclear if they played much of a role after Pyongyang announced in late November and in January that it had completed its state nuclear force.

Kim reiterated this in April and said that the North “no longer needs” to test its weapons capability. Last month, in front of foreign journalists, the North demolished the last three remaining tunnels as well as a number of buildings at its Punggye-ri nuclear test site, though experts later raised questions about the ability to quickly reverse this.

“Any agreement with North Korea must build on the current nuclear test suspension and ultimately include the dismantlement and removal of all nuclear, chemical, and biological weapons from North Korea,” the letter said. “Sanctions relief by the U.S. and our allies should be dependent on dismantlement and removal of North Korea’s nuclear weapons and ballistic missile programs.”

Any deal that “explicitly or implicitly” gives the North sanctions relief “for anything other than the verifiable performance of its obligations to dismantle its nuclear and missile arsenal is a bad deal,” it added.

In a nod to Seoul and Tokyo, the letter also highlighted the key role the two allies need to play in negotiations.

“To be successful in such an ambitious undertaking, our regional allies — in particular the Republic of Korea and Japan — are indispensable to our success,” it said, referring to South Korea’s formal name. “No concessions should be granted that could undermine our core alliance commitments or our posture in the region.”