The 14 Marines recently killed in Iraq by a roadside bomb came two days after hostile fire killed six other U.S. Marines from the same battalion.
Rising U.S. casualties and precision attacks have some wondering if the Iraqi police force has informants among its ranks foiling U.S. efforts. The Pentagon has admitted such infiltration exists, but experts warn it is hard to prove and the success of the attacks may have more to do with the insurgency's might than turncoats leaking inside intelligence.
"There is no question that the war in Iraq involves serious problems with infiltration at virtually every level," said Anthony Cordesman, a military analyst for ABC News. Although screening and vetting processes have improved, there is no way to guarantee absolute loyalty among the 173,000 personnel in the military, security and police forces and the large mix of civilian bureaucrats and contractors, he said.
The Pentagon expressed those exact concerns to Congress on July 21 with a report saying that the Iraqi "Commando" and "Special Forces" are improving, but that border control units remain weak, with a high level of infiltration by insurgent groups. The report rates other Iraqi security forces, with most having what the report calls "unknown" levels of insurgent infiltration. The overall conclusion of the report was that only a small number of these forces can operate independently.
At Wednesday's Pentagon briefing, no one blamed infiltration as a reason for the recent spate of deadly attacks.
"We have seen over the past few months a general decline in the number of improvised explosive device attacks," said Brig. Gen. Carter Ham, adding, "But the lethality has remained very, very high."
Ham blamed the rising death toll on the insurgency's use of different techniques and larger amounts of explosives to counter the efforts of Iraqi security forces and U.S. troops.
Cordesman credits the United States for pulling off a number of operations without a hitch, saying that infiltration usually doesn't compromise most missions. As for the less-successful missions, he said thwarting the military can be relatively easy because of the predictability of their movements.
"Most routes -- paved, dirt, or path -- are highly predictable and preparing roadside bombs and ambushes in advance can be very effective without intelligence," Cordesman said. He warned that it is very difficult to prove if someone is leaking "inside" knowledge.
The recent attacks have occurred in a desert-like landscape known as a troubled spot. The 50-mile stretch along the Euphrates, called the Hit-Haditha corridor, serves as a conduit for insurgents to transit people, weapons, money in and out of Baghdad, according to the Pentagon.
Ham called it the "nasty stretch" and said now that coalition forces have started cracking down, the insurgency's feeling the heat and rebelling any way it can.
Michael O'Hanlon, a senior fellow at the Brookings Institution, believes that despite the potential infiltration, the fundamental problem has more to do with the insurgency's ongoing support making coalition forces and the Iraqi police preferred targets, rather than with infiltration of those forces.
"I think there's a fair amount of intimidation of Iraqi forces by insurgents and you can do a lot of that without being on the inside," he said. Support for the insurgency has been fueled by discontent among Iraq's Sunni minority with the new government, and over time they have become very good at targeting U.S. forces, he added.
O'Hanlon stressed that both U.S. and Iraqi troops would be better served if security for the Iraqi forces was beefed up to perhaps retaliate against scare -- and death -- tactics.
RAND political scientist and terrorism expert Seth Jones went one step further, questioning the Iraqi security forces themselves.
"It's less of an infiltration issue than a loyalty issue," he said. Many of these security forces formerly belonged to brigades or militias and they still feel more allegiance to their brigade rather than to the Iraqi government, he explained.
Jones said that overall, having Iraqi forces fight with coalition partners hasn't been very successful, although he admits it is part of the nation-building process. That said, he warned that historically it takes nine years to effectively beat an insurgency, and so far the Iraqi resistance has stayed one step ahead of coalition forces, ambushing them every chance they get.
And Jones said he expects the situation to worsen.
"As U.S. forces begin to move out, that's when there will be real concern of infiltration among the compromised Iraqi forces," he said.