BAGHDAD, Iraq – All signs point to a major drawdown of U.S. troops in Iraq in 2006 – perhaps to fewer than 100,000 by year’s end. But it is far from certain when there will be further reductions, or a total pullout, after that.

In fact, it now looks as if the United States may have a long-term and substantial military presence in Iraq, military experts say.

Generals have been reluctant to set specific public timetables, but Gen. George W. Casey Jr., the top U.S. commander, noted this week that insurgencies in the 20th century lasted on average nine years. The Iraq war is coming up on year three.

“Because of the nature of counterinsurgency, it’s often hard for people to define what victory is,” Casey said. “It’s not D-Day. There’s not a big battle and it’s all over. It’s about people making choices so it evolves over time. And that’s exactly what you see here.”

The number of American troops here now is 136,000 – down from a December high of 160,000 troops, whose ranks were bolstered to protect against attacks during the Dec. 15 voting.

Casey is expected to recommend more cuts this spring. There’s speculation that by the end of this year, fewer than 100,000 U.S. troops will be in Iraq.

All that is predicated, however, on deploying more trained Iraqi army and police units to maintain security and to fight the insurgents. It also depends on the ability of the Iraqis to put together a government that can win the trust of disaffected Sunni Arabs, the backbone of the insurgency.

Talks on a new government will accelerate after the election commission releases certified figures from the December balloting this week. Still, it could be June before a new government is in place.

If all goes according to plan and security improves, the Americans will gradually withdraw from Iraqi cities and – over time – from the country itself.

“I wouldn’t want to put any number on (a drawdown) but I think I’ve said very consistently as the Iraqis assume more security responsibility, you’ll see us move to a supporting role, and reduce first our visibility then our overall presence,” Casey said in an interview with The Associated Press and National Public Radio.

That process, however, won’t happen overnight. Casey would not predict how long the insurgency might continue – with or without American troops at the forefront. But he said that bringing peace and stability to Iraq will take time.

“It’s also going to take time for (the Iraqis) to address the root causes of the insurgency and the long-term political and economic development problems they have,” Casey said. “And it’s not going to happen overnight.”

Some analysts believe the process is only just beginning. Despite gains against the insurgents in areas such as Mosul and Saleheddin province, U.S. deaths have been running steady for the past two years at about 50 to 75 a month with 500 wounded each month.

“I don’t see any sign over the past year that this will end anytime soon. … I don’t see any development that would indicate ‘light at the end of the tunnel’,” said Bruce Hoffman, a counterinsurgency expert with the Rand Corp.

Ahmed S. Hashim, a counterinsurgency expert at the U.S. Naval War College, predicted the U.S. is in for a “protracted stay” in Iraq, guiding the Iraqis in their struggle against the insurgents for years.

American forces remain in Germany, Japan and South Korea more than a half century after the conflicts that put them there.

Kenneth Pollack, a military-security expert at The Brookings Institution, estimates it will take at least four to five years before Iraq is ready to stand on its own without some kind of U.S. presence.