The Bush administration says Russian firms are continuing to provide Iran with technology for weapons of mass destruction despite persistent U.S. complaints.
A senior administration official says the United States has evidence that the weapons cooperation between Russian companies and Iran is continuing despite Moscow's stated opposition to such activity.
The official, who spoke to reporters here on condition of anonymity, said the trade cannot have escaped the attention of Russian intelligence, and said the government of President Vladimir Putin needs to "confront this contradiction" in its own policy.
The official declined to specify what kind of assistance the Russian firms were giving Iran, but said help for Iran's nuclear program "tops the list."
Russia agreed in March to renew weapons sales to Iran and to help that country complete construction of a controversial nuclear power plant on the Persian Gulf.
But Moscow has said the arms sales will be defensive in nature and that will not contribute to the proliferation of weapons of mass destruction.
The United States suspects Iran has a covert nuclear weapons program and that technology provided for the power station will assist that effort.
The senior official called the Iranian issue a "sore point" in a generally-improved U.S. relationship with Moscow.
He predicted the two sides will eventually resolve their dispute over the 1972 Anti-Ballistic Missile Treaty and that in the end Moscow will be "prepared to accommodate" a limited U.S. missile defense system aimed at countering weapons from so-called "rogue states."
He said the State Department's chief arms control official, John Bolton, will meet senior Russian officials in Europe in about week for more talks on the subject, and that Secretary of State Colin Powell will carry on the dialogue when he meets Russian Foreign Minister Igor Ivanov on the sidelines of the U.N. General Assembly session later in the month.
On another issue, the senior official said there is no indication Moscow is looking for a political solution to the conflict with separatist rebels in Chechnya.
He said the new American ambassador to Moscow, Alexander Vershbow, intends to visit the troubled region in a few weeks to underline U.S. concern about the situation.