The United States on Friday expelled the chief intelligence officer at the Russian embassy in a slow-motion reaction to revelations of a Russian "mole" inside the Central Intelligence Agency.
After several days of waiting for Moscow to make amends on its own, the Clinton administration lost patience and ordered Washington-based diplomat Aleksander Lysenko to leave within seven days.
As the senior intelligence officer here, Lysenko is presumed to have been the main contact for Aldrich Ames, a veteran CIA officer who, along with his wife, was charged this week with selling CIA secrets to Moscow for nearly a decade.
The Russians protested the expulsion. It was the first time since 1986 that the United States had expelled a Russian diplomat. It was expected that Moscow will retaliate by tossing out an equally high-ranking CIA official working in Russia, repeating the tit-for-tat pattern familiar in the Cold War era.
State Department spokesman Michael McCurry said there could be actions against other diplomats "who are subsequently implicated in the Ames affair." There have been strong hints that the CIA is searching for another spy in its ranks.
President Clinton took an unusually high profile role, calling on Moscow to take corrective action on their own, even as he attempted to maintain the aura of closeness with Russia.
At a news conference shortly before the expulsion, Clinton repeatedly reaffirmed his hopes for cooperation.
"It is in our national interest to continue working with Russia to lower the nuclear threshold, to support the development of Russia as a peaceful democracy, stable and at peace with its neighbors," he said.
Clinton said he had hesitated to expel the diplomat because his national security advisers favored giving the Russians "an opportunity to take whatever action they wanted to take" first.
The spy episode has provided opponents with fresh ammunition in their battle against sending billions of dollars in U.S. aid to Russia.
_ Information from the Associated Press was used in this report.