Many U.S. troops say it's one more broken promise. They landed in Iraq planning to rotate out after six months. Then Washington extended their stints to a full year. That was the limit, the Pentagon swore: just "365 days, boots on the ground," not a day longer. But last week the brass announced the decision to raise U.S. troop strength in Iraq by 12,000--meaning, among other things, that roughly 10,000 Americans now in Iraq can count on stretching their stay to 14 months. The new boost, the biggest since March 2003, will bring America's military presence in Iraq to 150,000. That total is more than it took to invade Iraq in the first place.

No one knows how long the buildup will last. The reinforcements are needed, and not only to provide security for the Jan. 30 elections. Last month's U.S. assault on the insurgent-held city of Fallujah may have been a success, but the aftermath has been a disaster. On the highway to Baghdad's main airport, suicide bombings have gotten so frequent that last week the American Embassy officially declared the road off-limits to its personnel. Now, U.S. diplomatic staffers need helicopters to get to the airport from the Green Zone. Mosul, six times Fallujah's size, is now almost as much of a no-go zone as Fallujah ever was. Thousands of Iraqi police have fled their posts, and more murdered bodies of Iraqi National Guardsmen turn up every day.

Worse, the elections may end up sucking U.S. troops deeper than ever into the morass. By Jan. 30 election officials want only Iraqis openly standing guard at the country's polling places, with no U.S. forces in sight to upset voters. But insurgents are targeting Iraq's security forces. Last week alone, attacks on police facilities in Ar Ramadi and Baghdad left at least 57 officers dead. Many cops on street patrol in Baghdad now wear masks to hide their identities. Without U.S. military backup, Iraqi security forces could be decimated on Election Day--dealing a drastic setback to the planned security handover that is vital to America's exit strategy.

The Iraqis' chief U.S. trainer insists he's not worried. "There's no shortage of recruits" despite the insurgent attacks, says Lt. Gen. David Petraeus. "We have more candidates than we have spaces." Large numbers of new Iraqi forces will be deployed in the next few weeks, he promises. And he was elated by reports on Friday that Mosul cops succeeded at last in fighting off insurgent attacks at four police stations.

The administration's critics say a U.S. troop buildup is long overdue. "We should have leveled with the American people to begin with--absolutely, positively necessary to do this four months ago, six months ago, eight months ago," said Democratic Sen. Joe Biden on a visit to Baghdad last week. "If I sound like I'm angry, it's because I am." Even so, senior officers insist the boost is only temporary. Otherwise the Army is in for a desperate scramble. The brass is convinced that reneging on the "365 days" pledge would send re-enlistments plunging. And there simply are no remaining units stateside to replace those troops who are sent home.

Senior officers roll their eyes at warnings of "mission creep." Their planners are hoping to solve the troop shortage by "embedding" small squads of Americans with Iraqi police forces and other security units. Military analysts say the Iraqis are reliable fighters when teamed up with U.S. or Coalition forces. They'd better be. The election is only the first in a yearlong series of stress tests--a constitutional convention, a nationwide vote on the draft constitution, another round of national elections--and, to top it all off, many of America's Coalition partners are now saying they want to bring their forces home within the year. "War's a tough thing," the Joint Chiefs of Staff chairman, Gen. Richard Myers, observed last week. "When you commit to war, you commit to a situation where you don't always have control." U.S. troops in Iraq know exactly what he's saying.