Robert Hanssen: Accused of spying for Russia since 1985

And the Americans can take some comfort from having stopped the continuing haemorrhage of secrets.

The security breaches have been detected and the appropriate counter-measures taken to assess the damage and prevent further similar episodes.

But from the Russian perspective, the picture is rather bleaker.

While Ames and Hanssen were selling their information to the Russians, the CIA was undertaking more than a dozen of its own recruitments in Moscow.

Furthermore, both the KGB and its post-Soviet successor, the SVR, have been beset by a steady stream of defections.

In particular, the loss of Vasili Mitrokhin, who smuggled out thousands of classified KGB documents before defecting to the UK in 1992, was a body blow to the prestige of the old KGB - and for the SVR, which evidently inherited many of its predecessor's assets in the West.

Warning to Kremlin

The north Americans now have a rich knowledge of current SVR operations there.

This ranges from clues to the identity of individual sources, such as Robert Hanssen, to the order-of-battle of the SVR field offices across the entire north American continent.

Counter-intelligence agencies need such a fundamental understanding of the adversary's capabilities to mount effective operations.

But once there is incontrovertible evidence of a large-scale espionage offensive, the matter takes on a political dimension. A decision has to be taken about whether such activities can be allowed.

The new American administration is sending a distinct signal to the Kremlin by deciding to expel the culprits.

The message is that intelligence collection will be tolerated for treaty verification purposes, but wholesale espionage will not.

Advantage America

On the balance sheet of international espionage, the losers in March 2001 are unquestionably the Russians.

The expulsion of so many professionals will disrupt their operations for at least two years and lead to the early deployment of ill-prepared replacements.

The heavy investment in the SVR officers who have been expelled will be largely wasted - they cannot be transferred to other Nato countries once they have been declared persona non grata in the US.

That disadvantage, combined with the loss of their double-agent Robert Hanssen and the continuing uncertainty about who has been compromised by the defection of Vasili Mitrokhin, will handicap the SVR for the foreseeable future.

For the CIA and FBI, on the other hand, there is an opportunity to be exploited.

Hanssen has been eliminated permanently from the espionage game, the damage control exercise is under way, and all future SVR attempts to re-establish their networks will severely hampered by FBI surveillance.

For now the score is SVR 2, CIA 4.

Nigel West is an author and military historian specializing in intelligence, counterintelligence, and security issues. He has published a number of books on espionage including The Crown Jewels and Counterfeit Spies.