The United States should significantly bolster defensive and offensive military capabilities, drive up sanctions and take other tough measures against North Korea if yet another attempt at diplomacy fails to persuade Pyongyang to move toward denuclearization, US experts said Tuesday.

Joel Wit, a North Korea expert with Johns Hopkins University's US-Korea Institute, made the case in a joint article with Richard Sokolsky, a senior fellow at the Carnegie Endowment for International Peace, arguing what they call "coercive diplomacy" stands a chance of success with the North.

"It would lead with diplomatic engagement with the North backed by the threat of robust military and economic actions to protect the United States and its allies from an expanding North Korean nuclear program," the experts said in the article carried by the Politico newspaper.

In an effort to give diplomacy a shot, US President Donald Trump should send a private message directly to the North's leadership that his administration is willing to explore peaceful paths forward, they said. The purpose would be to start preliminary talks without preconditions to explore whether diplomacy has a chance, they added.

The broader objective of such "coercive diplomacy" would be to reach a deal with the North in which the communist nation denuclearizes in phases in exchange for concessions that "would, in the eyes of Pyongyang, end the US 'hostile policy' toward the North, they said.

"If this initial effort at diplomacy fails, the Trump administration would be on a much firmer foundation having proved the North's diplomacy was a ruse and faced with a growing ICBM threat to contain the threat by significantly raising the pressure," they said.

Such measures should include expanding missile defense systems at home and in South Korea and Japan; bolstering offensive strike capabilities; making rotational deployments of nuclear-capable aircraft; and seeking stronger multilateral sanctions, they said.

"A new policy that tries negotiations first, and then puts intense pressure on the North if its intransigence scuttles diplomacy, is no guarantee of success, but the risks of trying this approach and failing are far outweighed by the costs and consequences of applying more sanctions, military force or seeking regime change," the experts said. 

"To paraphrase what Winston Churchill said about democratic forms of government, negotiating with the North is the worst option except for all others," they said. (Yonhap)