U.S. Undersecretary of State John Bolton on Thursday tried to play down any disagreements between the U.S. and Japan over Tokyo's oil development deal with Tehran.

"I am not troubled by (Japan's decision) at all," Bolton said in Tokyo. "I'm very confident that the view of Japan and the United States on the Iranian nuclear weapons program is essentially the same."

Bolton apparently worried that Wednesday remarks by U.S. State Department spokesman Richard Boucher created an unanticipated stir in Japan.

Boucher expressed concern toward the Japan-Iran oil deal because the Islamic state is suspected of developing nuclear weapons and supporting terrorist groups.

"Our policy has been, with respect to Iran, to oppose petroleum investment there," Boucher said in Washington. "We remain deeply concerned about deals such as this, and disappointed that these things might go forward."

Bolton said Japan's decision will not damage bilateral efforts to urge Iran to abide by its obligations under the Nuclear Nonproliferation Treaty and International Atomic Energy Agency.

A source meanwhile said the U.S. currently has no plans to invoke a U.S. law that requires Washington to impose sanctions on international firms doing business with Iran and Libya.

Information from Kyodo added