Ana Belén Montes didn't fit the profile of a spy. Neither did FBI agent Robert Hanssen. Yet both burrowed undetected for years in highly sensitive intelligence jobs while compromising U.S. national security.

Federal agencies must find better ways to uncover moles in their ranks. The United States is plowing re- sources into identifying terrorists. It's senseless to allow spies to undermine us from within. Why did it take 16 years to uncover Montes, who on Tuesday pleaded guilty to espionage?

She had already been recruited by Cuban intelligence when she joined the Defense Intelligence Agency in 1985, according to the Justice Department. By the time U.S. authorities caught up with her last year, she was considered the Pentagon's top Cuba analyst. By then she also had identified at least four U.S. intelligence agents for her Cuban handlers.

U.S. authorities said that none of the four betrayed by Montes were physically harmed. Unfortunately that wasn't so with the U.S. operatives that Hanssen gave up to the Soviet Union, some of whom were killed.

Montes's arrest was triggered by the Sept. 11 attacks. Cuba has cooperative intelligence relationships with Iraq, Iran and Libya -- and the four countries are on the State Department's terrorism blacklist. U.S. authorities didn't want Montes to leak sensitive data that could end up in the hands of fellow terrorist countries.

So far, Cuba has remained mum on Montes, as it did when its Miami spy ring first came to light. Convicted on multiple espionage charges in December, five Cuban spies argued that they only wanted to protect the communist island from Miami exiles -- not compromise U.S. national security.

What will be the regime's excuse for Montes? She had security clearance for access to ''top secret'' information whose unauthorized disclosure, by definition, ''reasonably can be expected to cause exceptionally grave damage'' to U.S. security.

Montes aided and abetted a totalitarian regime that would destroy us, if only it could. She was a stooge for a dictator who stays in power by oppressing his people. If she really wanted ''to help the Cuban people,'' she should have helped liberate them from Fidel Castro.

The U.S. intelligence community must thoroughly reassess attitudes and policies toward Cuba. A respected analyst within military circles, Montes shaped the opinions of high-ranking generals and members of Congress over the years. She was the architect of the 1999 Defense Department study that found Cuba no longer a military threat to the United States and was a proponent of closer U.S.-Cuba military ties.

U.S. intelligence and law-enforcement agencies must find a better way to flush out the spies, like Montes, who aim to cause the United States grave harm. Whether it takes im- proved hiring methods and better monitoring and polygraph testing, such security breaches must be stopped.