WASHINGTON –President Donald Trump’s meetings with North Korean leader Kim Jong Un in 2018 and 2019 did nothing to limit North Korea ‘s nuclear program and instead gave North Korea legitimacy, an expert with the Center for Strategic and International Studies told a Senate Foreign Relations subcommittee hearing on Tuesday.

Kim and Trump held a summit this time last year in Hanoi, Vietnam to negotiate the North’s denuclearization. The summit ended abruptly without any progress on efforts to dismantle North Korea’s nuclear weapons program. A year earlier Trump met with Kim in Singapore to open denuclearization talks.

East Asia Subcommittee Chairman Sen. Cory Gardner of Colorado said the U.S. should get tougher with Kim.

“It is time to go back to plan A on North Korea: the successful policy of maximum pressure that was adopted early in the Trump administration but since has been abandoned in an earnest effort of diplomatic engagement with Pyongyang,” he said.

North Korea continues to exploit gaps in U.S. enforcement of its sanction policy, said Gardner.

Center for Strategic and International Studies Senior Fellow Sue Mi Terry agreed.

“We should extend pressure on North Korea’s money launderers, facilitators and enablers,” she said. “We are currently well positioned to build on existing North Korean nuclear sanctions.”

She supported the idea of meetings between Trump and Kim but added, “we have not gained anything since Singapore two years ago. We’ve only given North Korea legitimacy.

The top Democrat on the subcommittee expressed disappointment that the Trump administration had not provided a witness for the hearing.

“It’s a snub to this committee,” said Massachusetts Sen. Ed Markey. “North Korean ballistic missile tests have rattled our allies. The Trump administration should put pen to paper. The U.S. will not tolerate nuclear tests of any range.”

“Since Hanoi, North Korea has more material for nuclear weapons and more confidence in their sea and land base ballistic missiles that put the continental United States and its allies in their cross hair”, said Sen. Markey.

CSIS Senior Fellow Robert R. King criticized the U.S. timidity in criticizing North Korea’s human rights abuses.

“Our foreign policy on North Korea should reflect our national commitments on human rights,” King said.