"I think there's at least some chance of a modest acceleration," this year, Gates said on his way back to Washington after a surprise Iraq visit for meetings with Gen. Ray Odierno, the top U.S. commander there, and local officials.
Under the Obama administration's current plan, two of 14 military brigades, roughly 10,000 troops, are scheduled to be withdrawn from Iraq by the end of this year. Gates said another brigade, or 5,000 troops, could come home by that time.
Gates said the consideration came because the situation is "better than expected."
However, continued bad blood between Iraq's Arab-led central government and the self-ruled Kurdish region in the north represents a major wildcard that could affect a faster pullout, Gates spokesman Geoff Morrell told news agencies.
Concern is growing that North-South tensions over land and resources could become a shooting war when U.S. forces leave. American military commanders say friction between Arabs and Kurds in northern Iraq is a key threat to security in the country, possibly overtaking the Sunni-Shiite divide that threatened to push Iraq into civil war three years ago.
During his surprise two-day visit, Gates pressured Kurdish leaders to resolve disputes with the Iraqi government in the next few months while the U.S. still has tens of thousands of soldiers in the country and U.S. leaders have greater influence over Baghdad.
In a meeting with Kurdish president Massoud Barzani, Gates cautioned that "very difficult issues remain and that the clock is ticking on our presence," Morrell said, according to the Washington Post.
Territorial disagreements between the Kurds and Baghdad, particularly over the oil-rich areas surrounding Kirkuk, have resulted in tense standoffs between Kurdish militia fighters and Iraqi army soldiers in the past few weeks.
The relatively affluent, peaceful Kurdish North is clashing with Prime Minister Nouri al-Maliki's government over its borders and resources. Gates met with Barzani, who claimed victory in a re-election vote last weekend that also saw large gains by an opposition slate, in Irbil, seat of the regional government.
The Kurds have been locked in a dispute with Baghdad over control of oil resources and a fault line of contested territory in northern Iraq, particularly the flash-point city of Kirkuk. The disagreements have stalled a national oil law considered vital to encouraging foreign investment.
Kurdish leaders say they are committed to staying in a unified Iraq, particularly since an independence push could alienate neighboring Iran, Syria and Turkey, which have their own Kurdish minorities. But Iraqi Kurdish politicians must answer to the strong nationalist sentiment among Kurds.
Gates told Barzani that the U.S. backs a set of United Nations recommendations to resolve some of the major disputes. Morrell would not characterize Barzani's response, except to say that Gates left the meeting "with the sense, just as he did in Baghdad, that the Kurds very much want to take advantage of our presence," according to media reports.
Barzani said recently that Iraqi and Kurdish forces were closer to violence than at any time since the fall of the Saddam Hussein's regime in 2003. The U.S. has liaison officers with both the Kurdish militia forces and the Iraqi Army troops.
The tension goes back decades to when Hussein's government attacked Kurdish villages with chemical weapons and razed much of its infrastructure in the years prior to the first Gulf War.
The United States has about 130,000 forces in Iraq, with current plans calling for most combat forces -- or more than 100,000 troops -- to remain in the country until after Iraqi national elections in January.
Gates gave no other specifics, and stressed that the accelerated withdrawal idea is preliminary and tied to continued good news in Iraq.
"It depends on circumstances; it may or may not happen," he said.
Violence is at an ebb in Iraq, and Odierno said Tuesday that he has been pleasantly surprised at how few problems have arisen following a June 30 handover of control of Iraqi cities.
He identified the tension in northern Iraq as the "No. 1 driver of instability."
"Many insurgent groups are trying to exploit the tensions," Odierno told reporters Tuesday. "We're watching very carefully to see that this doesn't escalate."
---- Compiled from wire reports and other media sources