Tokyo ? The United States is working with its allies on ways to punish North Korea for its development of nuclear weapons in violation of an international agreement, a senior U.S. defense official said Friday.

U.S. Undersecretary of Defense Douglas Feith said he and Japanese officials discussed halting shipments of fuel oil to the isolated communist state and stopping the construction of nuclear reactors to pressure Pyongyang. No decisions have been reached.

“It’s important that the North Koreans understand that there is a price to be paid for violating their commitments and pursuing a capability that threatens the peace and security of the region,” Feith said at the U.S. Embassy in Tokyo. “The challenge is devising a way of imposing a price so that diplomacy can work.”

Feith met with Foreign Minister Yoriko Kawaguchi, Defense Minister Shigeru Ishiba and other top officials.

Feith offered few other details except to say the campaign must consider countries such as Japan, South Korea, Russia and China, as well as the European Union.

North Korea told U.S. officials last month that it has been secretly developing nuclear weapons in violation of a 1994 pact with Washington.

Under that agreement, North Korea promised to freeze a plutonium-based nuclear program in return for two light-water nuclear reactors to meet its energy needs. The United States also agreed to supply North Korea with heavy oil until the reactors were up and running.

Construction of the reactors is years behind schedule.

U.S. Assistant Secretary of State James Kelly was to continue reviewing these issues when he and his counterparts from Japan and South Korea stage a regular meeting today on North Korea.

Feith also said he and Japanese officials discussed Japan’s request that Washington pardon Charles Robert Jenkins, the former U.S. Army soldier who allegedly defected to North Korea. He said no decision had been made.

Jenkins of Rich Square, N.C., is the subject of an intense tug-of-war between Tokyo and Pyongyang.