It will be more than a little ironic if the president who rode into office on anti-war sentiment ends up having to recommit to fighting in Iraq in the final years of his administration:

WASHINGTON — President Obama is open to expanding the American military footprint in Iraq with a network of bases and possibly hundreds of additional troops to support Iraqi security forces in their fight against the Islamic State, White House officials said on Thursday.

As Iraqi forces struggle on the battlefield, aides said Mr. Obama would consider establishing a series of outposts where American advisers would work with Iraqi troops and local tribesmen. The bases would be run by Iraqis, and Americans would still not engage in ground combat, but they would play a more active role closer to the front lines.

White House officials stressed that no proposal has been presented to Mr. Obama and added that they anticipated no decision in the next few weeks. But the prospect of further escalation came a day after the administration announced the opening of a new base in Anbar Province, an Islamic State stronghold, with an additional 450 American troops, bringing the total in Iraq to 3,550 — the size of a typical Army brigade.

Administration officials said they would evaluate whether that new Anbar base makes a difference in coordinating the war effort and, if it does, would consider replicating the approach in other parts of the country. Although officials said it was possible other bases could be opened without again sending more American troops, they acknowledged that more bases could require additional deployments.

For Mr. Obama, who has long resisted being drawn into another ground war since pulling out all forces in 2011, the latest developments represented another incremental step back into a sectarian conflict he had once hoped to be done with by the time he left office. Supporters of a more robust effort against the Islamic State called it a welcome if inadequate step to make good on the White House’s vow to defeat the Islamic State, while critics warned of sliding into a broader, bloodier and ultimately ineffective campaign.