WASHINGTON -- US President Donald Trump urged China on Monday to tightly control its border with North Korea until after he signs a nuclear deal with the regime.

Trump is set to meet with North Korean leader Kim Jong-un in Singapore on June 12, although Pyongyang has threatened to pull out of the summit.

"China must continue to be strong & tight on the Border of North Korea until a deal is made," he wrote in a tweet. "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!"

China has been a key player in the Trump administration's "maximum pressure" strategy to put increasing economic and diplomatic sanctions on Pyongyang until it gets rid of its nuclear weapons program.

Last week Trump said China could be behind North Korea's sudden threat to call off the June 12 meeting aimed at discussing denuclearization. He assured Pyongyang he would provide strong security guarantees if it agrees to dismantle its nuclear program, but also warned it could meet the same fate as Libya's toppled regime if it does not strike a deal. (Yonhap)