U.S. and Japanese diplomats agreed Tuesday to maximize pressure on North Korea to resolve tensions over its nuclear program, while citing the need to be prepared for the worst if diplomacy fails, AP reported.

U.S. Deputy Secretary of State John Sullivan, after meeting his Japanese counterpart, Shinsuke Sugiyama, told reporters that the focus at the State Department is still on diplomacy to solve the problem and eventually denuclearize the Korean Peninsula.

“We must, however, with our allies in Japan and South Korea and elsewhere, be prepared for the worst should diplomacy fail,” he said. The U.S. must be prepared to defend itself and its allies, he said.