The military buildup in Iraq is about to end.

But as the last of the five additional combat brigades now heads home, it leaves the country far safer than it was a year ago. Yet it's still not ready to stand alone.

The departure of the 2nd Brigade, 3rd Infantry Division will lower U.S. troop levels there to roughly 142,000 U.S. troops by mid-July — at least 7,000 more than before the buildup began. But it also sets up pivotal election year questions about how many more can come home this year, and whether the decline in violence can be maintained by the fledgling Iraqi security forces.

A report due out Monday is expected to lay out significant political, economic and security progress in Iraq — with some violence statistics down by more than 80 percent over last year's numbers.

Attacks against coalition forces and civilians have dropped and Iraqis have been turning in weapons caches at record rates.

Still, a U.S. commander in Baghdad acknowledged Monday that the Iraqi troops remain dependent on coalition support for logistics, surveillance and intelligence, and nowhere in Iraq can they do the job completely alone.

"There are no areas ... that we would be willing to separate out right now to dedicate specifically to the Iraqi security forces," said Lt. Gen. Lloyd Austin, "We've been clear about saying that they're not there yet. There are still some things that need to be done."

Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, offered a glimmer of hope Monday that troop levels in Iraq will continue to come down this year. He said he hopes that if Iraq continues to improve, he will be able to free some U.S. forces by the fall to send to Afghanistan.

"Iraq is in a much better place than it was a year ago, across the board," said Mullen, speaking to a large gathering of military and civilian workers in the Pentagon auditorium. "We're not at the sustainable point yet, we're not at the irreversible point yet."

That assessment continues to be a flashpoint for members of Congress eager to pull more troops out of Iraq. And there is likely to be increased pressure now, as the presidential campaigns hit their strides and the election draws near.

There are currently 146,000 U.S. troops in Iraq, including 15 combat brigades. Before the buildup began early last year, there were fewer than 135,000 U.S. forces there. In an interesting twist of history, the 2nd Brigade, 3rd Infantry Division — which will mark the end of the so-called surge — was also the unit that led the initial charge into Baghdad in March 2003.

Even though there will once again be 15 combat brigades in the country, the total force will be larger than before the buildup because the number of support troops — including security and training units — has grown, and several of the combat brigades now serving are larger.

Military leaders have been reluctant to predict further troop cuts, although Gen. David Petraeus, the top U.S. commander in Iraq, told Congress in May that he is likely to recommend further troop reductions in Iraq but won't provide details until fall.

At the time, he said future cuts would depend on continued political, economic and security progress in Iraq.

On Monday, Austin said the average number of weekly attacks has been holding at roughly 200 this month, compared to more than 1,200 in June 2007 — a reduction of about 80 percent.

In addition, roadside bombs have plunged by more than 70 percent since last year, while the number of weapons caches found shot up by more than 85 percent compared to a year ago.