BAGHDAD — One bomber penetrated the secure compound of Iraq's most celebrated police commando unit. Another slipped into a mess hall where scores of Iraqi soldiers were sitting down for a meal.
Neither suicide attacker aroused suspicion for a very good reason: Both were Iraqi security officers.
Nearly 30 soldiers and police officers were killed and dozens were injured in the two bombings this month. The attacks at the headquarters of the elite Wolf Brigade in Baghdad and at an army base north of the capital highlighted the grave challenge Iraq is facing from infiltration by insurgents.
In his address to the nation Tuesday, President Bush again emphasized the role of the Iraqi army and police forces, which he said are progressing "in both the number and quality."
Amid dwindling U.S. public support for the war, the ultimate success of Iraqi security forces is a linchpin of the administration's hopes. "A major part of our mission is to train them so they can do the fighting, and then our troops can come home," Bush said.
But it is feared that rebels have a stealthy presence among those forces. Infiltration was a specialty of Saddam Hussein's security apparatus, and officials say many recent cases were directed by so-called former regime elements -- FRE in military parlance.
"We believe part of the FRE strategy is to infiltrate the security forces with elements under their control and to get them into positions of influence," Army Lt. Gen. John R. Vines, commander of the Multinational Corps, said in an interview here.
Authorities also suspect that insiders are providing insurgents with the identities of police and military commanders, who are being gunned down on an almost daily basis, typically on their way to or from work. Interior Minister Bayan Jabr has alleged that the names and addresses of police are even being sold on the streets, the motive often profit rather than politics.
The pool of possible infiltrators is large. About 1,600 "ghost names" have been discovered on interior's payroll, Iraqi officials said, and the search is continuing. Not all are suspected infiltrators, but many have access to bases and sensitive installations.
Most Iraqi soldiers and police have shown strong courage and commitment, particularly considering that they are generally poorly equipped compared to U.S. troops and more of them have been killed. But Iraqi officials and high-ranking U.S. commanders concede that Iraqis' ultimate effectiveness in a grueling counterinsurgency campaign hinges in no small part on eradicating rampant infiltration of the security forces.
"I think it is the greatest long-term threat to the security of the country," said a senior U.S. military officer, who, like several others interviewed about the sensitive topic, declined to be named. "How do you make sure that your security forces have not been infiltrated and compromised and they're not tipping off operations?"
It is especially disquieting, officials say, that the attackers at both Iraqi bases were themselves Iraqis -- not foreign jihadists, as most suicide bombers are thought to be.
On June 15, an Iraqi soldier sat down with about 100 colleagues in a cafeteria on a base in Khalis, northeast of Baghdad, witnesses said. He apparently was wearing a belt rigged with explosives.
"The next thing we heard was a loud explosion," recalled one of the survivors, who declined to be named. "It was like a tornado that swept the place."
The bombing killed 26 Iraqi soldiers and injured 38. Some later accounts indicated that the infiltrator may have been a contract worker dressed as an army man. But several fellow soldiers said he was one of their own.
In the Wolf Brigade attack, three commandos were killed when the infiltrator detonated his bomb inside their compound.
Infiltrators also pose a very real danger for U.S. troops who, more and more, work alongside their Iraqi counterparts. The Pentagon has yet to release its findings in the Dec. 21 suicide bombing at a U.S. Army mess hall in northern Iraq that left 22 American troops and contractors dead. The attacker was wearing an Iraqi military uniform, officials say, but Arab media reports indicated that the assailant may have been a Saudi impostor who circumvented tight security.
The risks posed by moles in security posts extend well beyond bombings. There is great concern here about insiders, acting for money or ideology, tipping insurgents to operations. U.S. commanders often wonder whether someone was alerted in advance in the frequent cases in which they and Iraqi allies arrive for raids to find that the targeted suspects have vanished.
In many cases, security officers' kin are told by insurgents that family members will be kidnapped or killed if they do not provide information, authorities say.