Senior U.S. government officials on Wednesday welcomed Tokyo's decision to impose additional sanctions on Iran over its continued pursuit of its nuclear program but urged Japan to take further action in line with other countries.

Robert Einhorn, the U.S. State Department's special adviser on nonproliferation and arms control, and Daniel Glaser, deputy assistant secretary for terrorist financing and financial crimes, were in Tokyo to discuss the North Korean and Iranian nuclear situation with the government.

Their visit came as Japan announced Tuesday that it would implement additional sanctions on Tehran, including a freeze on assets of organizations and individuals involved in nuclear and missile programs. The action followed U.N. sanctions in June. The U.S., European Union, Canada, Australia and other countries have added further national sanctions, as well. But there is some concern in Japan that sanctions could damage its relationship with Iran, which is a major supplier of oil.

Einhorn, however, stressed that sanctions like those taken by the EU, for example, would "not adversely affect" Japan's economy.

"We look forward to working with Japan in sending a strong signal to Iran and promoting a negotiated solution of the question of Iran's nuclear program.

"It's our strong belief that Japan can join some 30, 31 other responsible, advanced industrial states in a growing consensus to put greater pressure on the Iran regime, and it could take these steps without harming Japan's security."

Einhorn also stressed that the U.S. has no intention of making a deal with Pyongyang to resume six-party nuclear disarmament talks.