ON THE day that fighters for the Islamic State of Iraq and Greater Syria (ISIS) occupied part of a city close to Baghdad, Barack Obama announced a bold plan. It had nothing to do with the Middle East: the president plans to create the world’s largest marine reserve in the Pacific. The administration also announced a comprehensive framework to eliminate seafood fraud.

At the other end of Pennsylvania Avenue, Republicans in Congress were absorbed by the race for the position of majority whip in the House (see article), and enraged by the disappearance of e-mails from officials at the Internal Revenue Service responsible for singling out conservative groups for special scrutiny (see article). There were few reminders that six and a half years ago America had 180,000 troops stationed in Iraq to prevent the country from slipping into civil war, as now seems to be happening (see article).

The 4,500 American soldiers who died in that cause, and the hundreds of billions of dollars the country spent are, in the blunt assessment of Barry Posen of MIT, a sunk cost. Mr Posen reckons that a de facto partition is an acceptable outcome in Iraq, and that no vital interests of the sort that America should be willing to spill blood for are at stake there. This view has become mainstream (see chart). More than half of Americans think their country is less powerful than it was ten years ago, the highest share since the Pew Research Centre started asking the question in 1974. Accordingly, Americans feel less inclined to act as global policeman: the share who think America should “mind its own business internationally” is ten percentage points higher than at the end of the Vietnam war. Since before he was president, Barack Obama has said that America cannot fix Iraq. As he put it in 2008: “Iraq is not going to be a perfect place, and we don’t have unlimited resources to try to make it one.” Last month he set out some principles to govern the use of military power that fitted the national mood. America should use force, unilaterally if necessary, only when its core interests are threatened, he argued. He sketched out those interests with a thick enough pencil to make it unclear what they look like. Gains made by ISIS fighters in Iraq since then have added some definition. The capture of several big cities by people who have invented a new online genre, the war crime self-portrait, does not yet cross the threshold. What Mr Obama has done is tell Congress that he is sending 275 soldiers to Iraq to provide security at the embassy in Baghdad. He has also sent an aircraft-carrier, along with two smaller ships carrying cruise missiles, to the Persian Gulf. John Kerry, the secretary of state, has discussed the possibility of air strikes against ISIS fighters. Mr Obama has been more cautious, saying only that any military support being for Iraq’s government would be conditional on it doing a better job of including Sunnis and Kurds. Some in the administration drop broad hints that Nuri al-Maliki, Iraq’s prime minister, should go. Meanwhile, a White House official waves away questions about American air support as mere “speculation”. The practical objections to the use of air power are surmountable. David Deptula, a retired lieutenant-general involved in planning the air campaign during Operation Desert Storm in 1991, says that the vehicles carrying ISIS fighters from one city to the next would be “tailor-made” targets if they headed for Baghdad. Nor is it necessary to have boots on the ground to direct the planes or missiles: the air force coped without them for the first 40 days of Desert Storm and drones can now hover over targets for ten hours at a time, beaming pictures back to their operators.

What American forces cannot do from on high, says Mr Deptula, is push ISIS out of the cities it holds already. That could only be accomplished by the Iraqi Security Forces, perhaps with support from Iran. Iran’s involvement makes America’s calculation more complicated. Though the advance of ISIS fighters has put America and Iran in the strange position of rooting for the same side, the two countries are supporting different groups in Syria’s civil war. And preventing Iran from building a nuclear weapon is higher on America’s list of priorities than a stable Iraq. The White House has ruled out military co-operation with Iran to fight ISIS, though the two countries will talk about Iraq on the sidelines of negotiations about Iran’s nuclear capability in Vienna.

Faced with a choice between siding with Iran and watching Iraq slide into civil war, most Republicans have decided that it is easier to blame Mr Obama for being weak. John Boehner, the Speaker of the House of Representatives, accused the president of “taking a nap” while ISIS marched towards Baghdad. Karl Rove, a former close adviser to George W. Bush, told Fox news that Mr Obama had squandered the influence that America had in Iraq back in 2008. Mitch McConnell, the leader of the Republican minority in the Senate, has called for Mr Obama to present a plan. The president has made it clear that he wishes to consult with Congress. Thus far the debate resembles the build-up to the decision not to intervene in Syria after Bashar Assad’s troops used chemical weapons, though this time Mr Obama has not drawn any red lines.

More constructive critics, such as Senator Bob Corker, a Republican, have called for air assistance to the Iraqi security forces but only after Iraq’s government takes steps to win back support from Sunnis. It is possible that the president will order air strikes to halt ISIS’s advance, but America will do no more than that. Mr Obama has been consistent on Iraq. The invasion, he argued while running for office, had left America less safe and less able to shape events in the world. Iraq’s government, he added, was suffering from the armed version of welfare dependency: “we’ve learned that when we tell Iraq’s leaders that we’ll stay as long as it takes, they take as long as they want.” For its own good, he reasons, Iraq’s government must be left to fight ISIS.

Even with some American air support for the government forces, the likeliest outcome in Iraq, argues Ken Pollack of Brookings, a think-tank, is now a drawn-out struggle between militias loyal to different sects. If Mr Pollack is right, Mr Obama’s claim to have ended the war in Iraq—one of the proudest achievements of his presidency—will have to be modified. America’s involvement may be largely over, but the war America started continues.