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After watching the astonishingly quick takeover of important cities in Iraq, many are asking, how did a relatively small number of extreme Islamist fighters pull it off? After all, the militant group that swept out of Syria, known as ISIS, is only a few thousand strong. But its successes in Iraq have led President Obama to send 300 military advisers back to Iraq to beef up intelligence efforts with a joint operation center in the capital Baghdad. NPR's Deborah Amos has this report on how hard it will be for the Iraqi government to regain the territory it lost, even with U.S. help.
DEBORAH AMOS, BYLINE: Falah al-Nakib, a former interior minister in Iraq, says he's amazed at the lightning speed of an ISIS campaign to seize Iraq's Sunni heartland - amazed, but not surprised.
FALAH AL-NAKIB: The planners, the commanders, they are military officers.
AMOS: He knows some of the officers. He's come to Erbil to talk to them, to find an urgent solution as Iraq plunges toward civil war. They served in the old Iraqi army, he says, under Saddam Hussein, dismissed from their jobs by the U.S. after the invasion in 2003. Now they've allied with the radical Islamists of ISIS.
AL-NAKIB: Its military tactics, you know, they are professional commanders from the ex-Iraqi army.
AMOS: When we see the numbers of ISIS, it's not that many guys.
AL-NAKIB: ISIS, they don't present more than, the best scenario, 15 percent, I think.
AMOS: But the few thousand fighters are crucial, says Nakib. They are the Sunni shock troops with a fearful reputation of hyper violence mostly against Iraqi security forces, who are overwhelmingly Shiite Muslims. When ISIS arrived in Mosul, much of the Iraqi National Army abandoned their posts and ran.
AL-NAKIB: They use them in certain operations to make some kind of reactions among the military forces.
AMOS: The reaction to ISIS was confirmed by this former Iraqi colonel, reached by phone in Mosul. He agreed to talk on condition he is not named. He says he's part of a new military counsel running Mosul, after the Iraqi army dissolved, when ISIS used terror tactics in the streets.
UNIDENTIFIED COLONEL: They start with car bombs, with many cars. And after that, they will run away, leaving and their vehicles and even their weapons.
AMOS: That's the reason security forces left town. But the key to the militant success, they're able to exploit widespread Sunni anger with the government of Prime Minister Nouri al-Maliki, backed by Iran, the regional Shiite power. When ISIS arrived in Mosul, many Sunni residents greeted them as liberators. Dlovan Barwari, a Kurdish investigative journalist, says Sunnis joined the ISIS campaign in a kind of rolling recruitment, which explains the fast capture of Sunni towns across the North, as the militants march toward the capital Baghdad.
DLOVAN BARWARI: If ISIS get the city, that means they already have people inside the city.
AMOS: So each place that ISIS goes, they already have people who sympathize with them, so the army gets bigger?
BARWARI: Yeah, for sure. Like, all the - we can say all the Sunni's place, they have a people.
AMOS: The people, these Sunni groups, including tribal leaders, have deep roots in northern communities which could make it difficult for the Maliki government to reassert control. This is now a complicated set of strategic problems as the U.S. steps in, says Ali Khadery, who served as a political advisor in Iraq to U.S. ambassadors and military commanders from 2003 to 2010. There is the spillover from Syria, the terrorist threat, the threat to Baghdad. But in Iraq, the root cause is political and long in the making.
ALI KHADERY: Why have 6 million Iraqi Sunni Arabs risen up against the government in Baghdad? Because they have been disenfranchised by Prime Minister Maliki's sectarian, exclusive form of governance, backed up by the Iranian revolutionary guards from Tehran.
AMOS: Khadery says this Sunni-ISIS alliance may agree on military tactics, they often don't agree on goals. The ISIS militants have no interest in preserving the Iraqi state, but many of the Sunni tribal leaders and former army officers have political goals that can only be addressed in the Iraqi capital. Deborah Amos, NPR News, Erbil. Transcript provided by NPR, Copyright NPR.