WASHINGTON — U.S. Senate Democrats are demanding that any agreement President Donald Trump makes to ease sanctions on North Korea be contingent on complete denuclearization and destruction of test sites.

In a letter to Trump, seven senior Senate Democrats outlined the conditions of their caucus’s support for any deal that results from Trump’s planned summit next month with North Korean dictator Kim Jong Un. Senate Minority Leader Chuck Schumer, D-N.Y., and Senate Foreign Relations Committee Ranking Member Bob Menendez, D-N.J., also held a press call Monday.

“Now that the meeting will proceed as planned, [we] want to make sure the president’s desire for a deal with North Korea doesn’t leave the United States, Japan and South Korea with a bad deal,” Schumer told reporters.

While Schumer expressed hope for peace and a successful summit, he warned Trump “has to be willing to walk away from the table if there isn’t a good deal to be had.”

The letter presented five conditions for North Korea:

  • Dismantle and remove all of its nuclear, chemical and biological weapons.
  • End the production and enrichment of uranium and plutonium for military purposes, and permanently dismantle its nuclear weapons infrastructure. This includes destroying all test sites, nuclear weapons research and development facilities and enrichment facilities.
  • Suspend all ballistic missile tests and disable, dismantle and eliminate all of its ballistic missiles and programs.
  • Commit to robust compliance inspections including a verification regime for its nuclear and ballistic missile programs—and chemical and biological weapons. The regimes must include “anywhere, anytime” inspections and snap-back sanctions if North Korea is not in full compliance.
  • Agree that any deal must be permanent.

The letter was signed by Schumer, Menendez, Assistant Senate Minority Leader Dick Durbin, Senate Select Committee on Intelligence Vice Chair Mark Warner, Senate National Security Working Group Co-Chair Dianne Feinstein, Senate Appropriations Committee Vice Chair Patrick Leahy and Senate Banking Committee ranking member Sherrod Brown.

Though the presence of 28,000 U.S. troops in South Korea isn’t addressed in the letter, Schumer and Menendez said they might one day favor a withdrawal — at some point after North Korea meets all conditions, and working with America’s regional allies.

“To pull troops out at the beginning before anything else is done would be a very big mistake and the wrong signal,” Schumer said. “You have to see what the agreement is and how things are progressing. Removing troops early on would be a terrible signal to our allies and a terrible signal to North Korea itself.”

Defense Secretary Jim Mattis on Sunday told reporters en route to Washington, D.C., from the Shangri-La Dialogue security conference, that the 28,000 U.S. troops in South Korea are, “not going anywhere.” Though the topic could be up for review in five to ten years, he said, “It’s not even a subject of the [denuclearization] discussions.”

Trump, too, told reporters last month the troops would not be bargaining chip, “at this moment,” adding that he would “at some point in the future, I’d like to save the money,” associated with the arrangement in place since the 1953 Korean War armistice.

Over the weekend, Trump confirmed plans are moving forward for the summit with Kim on June 12 in Singapore. It’s the first between heads of the technically still-warring nations and meant to begin the process of ending North Korea’s nuclear program; Trump said he believes Kim is committed to that goal.

The president said it was likely that more than a single meeting would be necessary to bring about his goal of denuclearizing the Korean Peninsula. He said, “I think you’re going to have a very positive result in the end, not from one meeting.”

“I don’t even want to use the term ‘maximum pressure’ anymore,” Trump added, referencing his preferred term for the punishing U.S. economic sanctions imposed on North Korea in response to its nuclear and ballistic missile tests. But he said he would not remove current sanctions until the North took steps to denuclearize.

At the Shangri-La Dialogue, Mattis warned it will be a “bumpy road” to the nuclear negotiations with North Korea later this month. He told South Korean and Japanese counterparts they must maintain a strong defensive stance so the diplomats can negotiate from a position of strength.

Mattis repeated the U.S. position that North Korea will only receive relief from U.N. national security sanctions only when it demonstrates “verifiable and irreversible steps” to denuclearization.

The Associated Press contributed to this report.