President Trump urged China to be “strong & tight” on its border with North Korea until a nuclear deal can be worked out with the reclusive regime.

“China must continue to be strong & tight on the Border of North Korea until a deal is made,” the president said on Twitter Monday. “The word is that recently the Border has become much more porous and more has been filtering in. I want this to happen, and North Korea to be VERY successful, but only after signing!”

Trump is expected to sit down with North Korean President Kim Jong Un in Singapore on June 12.

He’s hosting South Korean President Moon Jae-in at the White House on Tuesday.

In a phone call over the weekend, Trump and Moon restated their commitment to making sure the historic summit takes place after Kim’s government began making demands and threatened to back out of next month’s meeting.

Trump has credited his “maximum pressure” campaign of crippling economic sanctions for pushing North Korea to the negotiating table.

He also enlisted China, North Korea’s largest trading partner, to pressure Kim on getting rid of his nuclear arsenal.

Kim’s regime said it wants the US to back away from demanding they completely relinquish their weapons and to put an end to joint military operations with South Korea.