(Matthew Bruch/AP)

Max Boot is a senior fellow at the Council on Foreign Relations. This commentary was adapted from a CFR Policy Innovation Memo.

President Obama’s strategy in Syria and Iraq is not working. The president is hoping that limited airstrikes, combined with U.S. support for local proxies, will “degrade and ultimately destroy” the Islamic State. But while U.S. actions may have blunted the Islamic State’s expansion, they have not shaken the terrorist group’s control of an area the size of Britain. If the president is serious about dealing with the Islamic State, he will need to increase America’s commitment well beyond his recent decision to deploy 1,500 more advisers.

What will it take to achieve the president’s objective?

●Intensify airstrikes. When the Taliban lost control of Afghanistan between Oct. 7, 2001, and Dec. 23, 2001 — a period of 75 days — U.S. aircraft flew 6,500 strike sorties and dropped 17,500 munitions. By contrast, between Aug. 8, 2014, and Oct. 23, 2014 — 76 days — the United States conducted only 632 airstrikes and dropped only 1,700 munitions in Iraq and Syria. Such desultory bombing will not stop such a determined force as the Islamic State.

●Lift the prohibition on U.S. “boots on the ground.” Obama has not allowed U.S. Special Forces and forward air controllers to embed themselves at the company level and go into combat as they did with the Northern Alliance in Afghanistan in 2001. This lack of eyes on the ground makes it harder to call in airstrikes and to improve the combat capacity of U.S. allies. Advisers fighting alongside indigenous troops are far more effective than trainers confined to big bases.

● Increase the size of the U.S. force. The current force, even with the recent authorization to expand to 3,000 personnel, is still inadequate to counter the 20,000-plus fighters of the Islamic State. Credible estimates of the necessary troop strength range from 10,000 personnel (retired Marine Gen. Anthony Zinni) to 25,000 (analysts Kim and Fred Kagan).

●Send in the Joint Special Operations Command. Between 2003 and 2010, JSOC — composed of units such as SEAL Team Six and Delta Force — became skilled at targeting the networks of al-Qaeda in Iraq. Its success was due to its ability to gather intelligence by interrogating prisoners and scooping up computers and documents — something that bombing alone cannot accomplish. JSOC squadrons should once again be moved to the region (they could be stationed in Iraq proper, the Kurdish region or Jordan) to target Islamic State organizers.

●Do more to mobilize Sunni tribes. Given Shiite militia infiltration, working exclusively through the Iraqi Security Forces would risk empowering the Shiite sectarians whose attacks on Sunnis are the Islamic State’s best recruiter. The United States should directly assist Sunni tribes by expanding the newly established U.S. outpost at al-Asad Air Base in Anbar province, and also increase support for and coordination with the Free Syrian Army and Sunni tribes in Syria. Current plans to train only 5,000 Syrian fighters next year need to be beefed up.

●Impose a no-fly zone over part or all of Syria. Even though U.S. aircraft are overflying Syria, they are not stopping dictator Bashar al-Assad’s forces from bombing rebel-held areas. This has led to a widespread suspicion among Sunnis that the United States is willing to keep Assad in power — a suspicion fueled by news that Obama sent a letter to Assad’s backers in Tehran proposing cooperation. Sunnis are not going to fight the Islamic State if the alternative is Iranian domination. A no-fly zone over part or all of Syria would save lives while rallying Sunnis to the anti-Islamic State cause, allowing the Free Syrian Army to expand, and possibly paving the way for greater Turkish involvement.

●Prepare now for nation-building. The United States should lay the groundwork for a post-conflict settlement in both Iraq and Syria that does not necessarily require keeping both political entities intact. In the Iraqi context, this means offering greater autonomy to the Sunnis (they should be promised Kurd-like autonomy) and guaranteeing the Kurds that their hard-won gains will not be jeopardized. The United States should offer to station troops for the long term in the Kurdish area and possibly Anbar, too. Social fragmentation in Syria will make reconstruction there harder. The U.S. goal should simply be to ensure that Syrian territory is not controlled by Shiite or Sunni extremists. The postwar settlement in the former Yugoslavia, which involved the dispatch of international peacekeepers and administrators under United Nations, European Union and NATO mandates, could be a model. This is admittedly an ambitious, long-term goal, but if no such plans are in place, as in Libya in 2011 or Iraq in 2003, failure is guaranteed.

Critics will call this strategy too costly, alleging that it will push the United States down a “slippery slope” into another ground war. But while this approach will undoubtedly incur greater financial cost and higher risk of casualties, the present minimalist strategy has scant chance of success and risks backfiring — the Islamic State’s prestige will be enhanced if it withstands half-hearted U.S. airstrikes. Left unchecked, the Islamic State could expand into Lebanon, Jordan, Turkey or Saudi Arabia, making a major ground war involving U.S. troops more likely. By contrast, this strategy would enhance the odds that the group could be defeated before Obama leaves office.