IT WAS intense. The barrage of Tomahawk missiles and precision-guided bombs launched against the jihadists who call themselves Islamic State (IS) in the early hours of September 23rd surpassed in just a few hours six weeks’ worth of American air attacks against the bits of IS on the Iraqi side of the now-effaced frontier. The attacks stood out in other ways, too. They were the fruit of an unusual military coalition, with five Arab countries not only prepared to join and assist the raids, but also to be identified as doing so. And they made America a fully fledged participant in Syria’s civil war, an entanglement Barack Obama has fought a three-year campaign to avoid. But this now exceptional undertaking may well be the beginning of a new normal. The defeat of IS will need a protracted effort.

When Barack Obama promised on September 10th that he would “degrade and ultimately destroy” IS few expected an attack on quite this level of “shock and awe” to be deployed so soon. Surely getting the right regional allies in line would take time, as would the choice of targets. But less than two weeks later Saudi Arabia, Jordan, Bahrain and the United Arab Emirates were joining in the attack, mostly flying American-supplied F-16s; Qatar provided logistical support.

That said, most of the firepower was American, with cruise missiles and waves of carrier-borne and land-based jets (including, for the first time in combat, the stealthy F-22 Raptor) backed up by armed drones. More than a dozen strikes were carried out against a variety of IS targets, many in and around Raqqa, a city which the jihadists took control of last year. They were identified as a headquarters building, a finance centre, training compounds, storage facilities, supply trucks and armoured vehicles. A separate series of eight missile strikes, carried out by American forces alone, targeted a hitherto obscure jihadist cell which American officials call the “Khorasan group” at several sites near Aleppo (see article).

United, for now

On September 24th five further strikes were reported on the Syrian-Iraqi border. Rami Abdul Rahman, who runs the Syrian Observatory for Human Rights, said there had also been raids west of the town of Kobane, also known as Ain al-Arab, near Turkey. One objective may have been to provide relief for Syrian Kurds struggling to hold out against an IS onslaught; if IS were to take Kobane despite being under air attack it would be a striking victory.

In Washington, Republican and Democratic leaders in Congress offered bipartisan support, broadly reflecting the changed mood of their constituents. Only last year, a war-weary American public hated the idea of getting involved in Syria. It disapproved even of limited cruise-missile strikes to punish Syria’s president Bashar Assad for using chemical weapons against civilians. Now IS is perceived as a direct threat to the safety of Americans, testimony to the power of atrocities promulgated via internet video—in this case the beheadings of two American journalists and a British aid worker.

But if America’s mood of unity is broad, it is also shallow. There is no consensus about whether its military might is being deployed to bring greater stability to the Middle East or whether the mission is much narrower: a counter-terrorist operation to neutralise threats at a distance, and thus protect Americans at home. Mr Obama has done little to clear that confusion up. He has said that IS is mainly a threat to the people of the Middle East, repeatedly declaring that “this is not America’s fight alone”. But he and his officials also make their mission sound like a counter-terrorist operation to protect people at home, using the phrase “a network of death” to describe IS. The strike on the Khorasan group fits into a debate dominated by talk of domestic security.

Surprisingly, perhaps, the Syrian government has not protested much. Its main beef is that America refuses to treat it as an ally against IS. “We are facing one enemy. We should co-operate,” says a government spokesman, Bassam Abu Abdullah. Some reports claim that key intelligence on the Khorasan group was supplied by Syria. Other sources in the region claim that the raids against IS near Kobane were carried out not by America but by Syria itself.

America insists that “there was no co-ordination and no military-to-military communication” with Syria; it only informed Syrian diplomats at the United Nations of upcoming raids, and Syrian radars were “passive”.

Syria’s apparent acquiescence makes the task of justifying strikes on its territory a bit easier. America argues that the raids were conducted on the basis of Article 51 of the UN Charter, which asserts the right to collective self-defence; in such cases neither a Security Council resolution nor the permission of the relevant government is required. America’s ambassador to the UN, Samantha Power, argued to its secretary-general, Ban Ki-moon, that Iraq had asked America to assist in defending itself from IS; that the group was using havens in Syria to mount attacks on Iraq; and that the government of Syria was either unable or unwilling to prevent this. It therefore followed that the strikes were legal.

The use of the “unable or unwilling” argument to trump national sovereignty, which is regarded as controversial by some international lawyers, has been employed in the past to justify American air strikes against militants in Yemen, Somalia and the tribal areas of Pakistan. Mr Ban appeared to accept Ms Power’s case. Some of the more than 40 nations that have pledged arms or support to the fight against IS may still wish to see the issue go to the Security Council. But with Russia in an adversarial mood over Ukraine, an authorising resolution is a remote prospect.

The legality of eagles

Greater clarity on the legal position could help one so far absent ally: Britain. The prime minister, David Cameron, lost a House of Commons vote on attacking Syria last year and could not afford to lose another. But having received a formal request for assistance from Iraq, he has recalled Parliament and will seek approval for military action in Iraq, leaving Syria for another day; the French, already flying missions in Iraq, make a similar distinction.

Turkey, another American ally not initially signed up to the attacks, seems already to have had a change of heart. On September 11th it refused to sign the “Jeddah communiqué”, in which various Arab nations promised to back America’s military action. Turkey’s president, Recep Tayyip Erdogan cited the safety of 46 Turks IS had taken hostage in Mosul, in Iraq. The captives were freed on September 20th amid rumours of a prisoner swap, or even worse; a new IS offensive against Syrian Kurds in their enclave of Kobane stoked Kurdish suspicions that the Turks had sold them out in some way. But on September 23rd Mr Erdogan declared that his country was ready to “give the necessary support to [the attacks on IS]. the support could be military or logistics.”

America’s clearest success has been to gain strong backing from habitually shy Arab states. Saudi authorities even released photos of pilots ostensibly returning from missions in Syria; two of them were princes from the ruling al-Saud family, including a son of the heir to the throne. King Abdullah of Jordan spoke bluntly of a struggle of good against evil.

The effectiveness of the strikes against IS remains to be seen. A further set of attacks on targets in Syria on September 24th aimed at disrupting oil sales by IS, which may be earning the group as much as $2m a day. But the jihadists have had plenty of time to hide important assets in population centres. And there is a palpable shortage of forces on the ground to exploit the air offensive. This applies not just in Syria (see article) but also to an extent in Iraq. Most Iraqi Sunnis have yet to be convinced by recent attempts to shape a more inclusive, less sectarian government in Baghdad. And while IS may have been halted in its march on Baghdad, the jihadists are still capable of inflicting defeats on the Iraqi army, despite its overwhelming numerical superiority and American air power. On September 21st IS overran an Iraqi army base 50km (30 miles) west of Baghdad, capturing or killing hundreds of soldiers. Days later another base was surrounded

More than a prod

Elsewhere in the region a range of relatively moderate Islamist groups, including the Muslim Brotherhood, have joined with IS in seeing the coalition as the spearhead of a new Western crusade. In Syria, even secular opponents of Mr Assad’s rule warn of the danger of alienating opinion among the country’s majority Sunnis. In Jordan’s parliament MPs have engaged in shouting matches over the country’s participation in the war.

Iran, meanwhile, is playing a complex game. It supports both the government in Iraq, an American ally if hardly a trusted one, and the one in Syria, supposedly an American foe. The country’s leaders have publicly condemned America’s renewed intervention in the Middle East, but some diplomats have quietly hinted that they might be able to co-operate in the downfall of IS—which Iran loathes—in return for better terms in the continuing negotiations over their country’s nuclear programme. Similarly, Egypt’s president, Abdel Fattah al-Sisi, said his country would be a stronger member of the coalition if America sped up delivery of military hardware.

On the morning after the first air strikes on Syria, a Pentagon commander, Lt General William Mayville, said the new campaign could last for years. It is far from clear that a fearful, terrorism-focused American public is ready for such a prolonged commitment. Mr Obama wants to use his country’s military power as a tool of geopolitical influence, which—by being withheld or used in the right way—can prod others in the region to assume their responsibilities and, as he said at the United Nations on September 24th, “explicitly, forcefully, and consistently” reject the ideologies of such organisations as al-Qaeda and IS. But such a clear message may not be easily heard above the din of civil war America has now joined itself to.

Correction: An earlier version of this article got its Jordanian kings mixed up. It was King Abdullah who spoke bluntly of a struggle of good and evil. This was changed on September 29th.