North Korea’s nuclear weapons development could be used as “blackmail” to influence the U.S. to abandon its ally in South Korea in order to make it easier for Pyongyang to overtake its archrival, a White House official said Tuesday.

Matt Pottinger, the Asia director on President Trump’s National Security Council, said there might be some truth to the idea that North Korea wants a nuclear deterrent to protect its communist regime, but the country’s robust conventional military has worked as a deterrent for decades.

"They have made no secret in conversations they have had with former American officials, for example, and others that they want to use these weapons as an instrument of blackmail to achieve other goals, even including perhaps coercive reunification of the Korean Peninsula one day," Pottinger said at a conference in Washington.

Pottinger said North Korea also wants the U.S. “to leave the peninsula and abandon our alliances.” He said the U.S. is not seeking a regime change in North Korea, but the U.S. wants the North to end its nuclear weapons program.

"We really have no choice but to increase pressure on North Korea to diplomatically isolate them, to bring a greater economic pain to bear until they are willing to make concrete steps to start reducing that threat," he said.

Pottinger’s comments come a day after Trump opened the door slightly to a future meeting with Kim Jong Un, saying he would be “honored” to meet with the dictator under the right circumstances. He also praised Kim as a “pretty smart cookie.”

Trump did stop short of drawing a red line with Kim in an exclusive interview on “The Fox News Specialists,” despite calling North Korea his biggest foreign policy concern.

“I don't like drawing red lines but I act if I have to act,” Trump told host Eric Bolling.

The U.S. strategy right now focuses on getting China to increase pressure on Pyongyang.

The U.S. has sent warships to the region to deter North Korea from conducting another nuclear test to advance its weapons programs. The North's nuclear and ballistic missile development already threatens South Korea and Japan, and within years could put the U.S. mainland within striking range.

The North also has a formidable array of conventional artillery and rockets trained on the heavily populated South Korean capital.

The Associated Press contributed to this report.