REBECCA ROBERTS, host:

With tensions between the U.S. and Russia running high at the G-8 summit, we thought we'd take a minute to look at the intelligence part of the relationship. U.S. intelligence officials say Russian spies are now as active in the U.S. as they were at the height of the Cold War. That's apparently a reflection of the priorities of President Putin, a former KGB man himself, and a sign that the strained diplomatic relations may be damaging U.S.-Russian intelligence cooperation.

Here's NPR's Mary Louise Kelly.

MARY LOUISE KELLY: Let's start with the fact that the Russians are hardly alone in their efforts to spy on the United States.

Mr. JOEL F. BRENNER (Executive, Office of the National Counterintelligence Executive): There are about 140 intelligence services around the world and the number one target of just about every one of them is the United States of America.

KELLY: That's Joel Brenner. He's in charge of all U.S. counterintelligence Efforts, counterintelligence being the business of identifying and dealing with threats from foreign spy services that are trying to steal U.S. secrets.

Brenner says the Russians are among the best in the business.

Mr. BRENNER: We tend to put them in bands or tiers, and we've identified Russia, China, Iran, and Cuba as the most persistent, pervasive threats that we deal with.

KELLY: Inside Brenner's offices in suburban northern Virginia runs a full wall of photographs. They call it the wall of shame - photos of Jonathan Pollard, Robert Hanssen and dozens of other Americans who worked as double agents selling American secrets. Most of these are Cold War era, many of those pictured sold their secrets to the KGB.

Joel Brenner says Moscow is now working as hard as it did during the Cold War to spy on the U.S. But he insists this is to be expected, given factors such as Russia's reenergized economy.

Mr. BRENNER: The Russian espionage against the United States is back to a normal level. In the '90s, the Russians were back on their heels in so many respects and espionage was just one of them. We're back at the norm now.

KELLY: But Dave Szady believes something noteworthy is going on here.

Mr. DAVE SZADY (Former Assistant Director, Federal Bureau of Investigation): They have raised their presence here greatly over the past few years and are continuing to do so.

KELLY: For six years, from 2001 until last year, Szady was the FBI's chief of Counterintelligence. He says there are probably more than a hundred Russian intelligence officers now inside the U.S.

In recent years, Szady says, Russia has gone a bit more creative about the covers its spies use. Some posed as business travelers or students, but mostly, the Russians continue to embrace a more orthodox approach.

Mr. SZADY: Their intelligence presence is in the United Nations. It is in the embassy. It is in the consulates throughout the United States. They're classic. I mean, they love that symmetrical one on one, spy versus spy, go get the people that can tell you what you want to know and use your intelligence officers to do it.

KELLY: So what is it that the Russians want to know? We put the question to Oleg Kalugin who ought to know, he's a retired KGB major general.

Mr. OLEG KALUGIN (Former KGB officer; Retired): The targets remain essentially the same: the penetration of major federal agencies of the United States.

KELLY: That is, Moscow wants to know what top U.S. leaders are thinking. Kalugin says other targets include military hardware and scientific know-how and technology from private American companies.

Mr. KALUGIN: These days, now, we will simply try to do our best to steal from these countries to acquire information, which will make Russia stronger.

KELLY: Oleg Kalugin now lives in Maryland. A few years back, he was convicted in absentia in Moscow for passing state secrets to the U.S. But Kalugin has vowed never to return and there's no extradition treaty in place that would allow Moscow to seek his arrest.

Today, Moscow and Washington are at odds over more sweeping issues: missile defense, NATO expansion and the war in Iraq, among others. Dimitri Simes, a Russia expert and president of the Nixon Center, believes the diplomatic tension is still turning down on two levels, causing Russian spies in the U.S. to act more aggressively and damaging existing intelligence cooperation.

Simes recalls a recent conversation he had with a senior Russian security official. The official was recalling the old joke among Soviet workers, which goes: the government pretends to pay us and we pretend to work for them.

Mr. DIMITRI SIMES (President, Nixon Center): Maliki said, Americans pretend that they share intelligence information with us and we pretend that we act on it. There is still a pretense of intelligence cooperation, but less and less substance.

KELLY: Joel Brenner, the U.S. counterintelligence chief, strongly denies this.

Mr. BRENNER: There are many aspects of Russian-American relations that are just going on business as usual now. And it would be a mistake to think that because we do have certain real disputes with the Russians, that there are - lot of areas where we are continuing to do business with them in a very effective way.

KELLY: Including intelligence sharing?

Mr. BRENNER: Including intelligence.

KELLY: Brenner adds even when diplomatic tensions run high, quote, "espionage isn't something you gin up overnight. It takes a long time to prepare; you don't just turn it on and off."

Mary Louise Kelly, NPR News, Washington. Transcript provided by NPR, Copyright NPR.