Washington ? Here’s a national-security riddle: How can President Obama provide limited military support on the ground to help “degrade and ultimately destroy” the Islamic State without formally violating his pledge not to send U.S. combat troops? The answer may lie in the legal alchemy known as “Title 50.”

Title 50 of the U.S. Code regulates the activities of the Central Intelligence Agency. An often-cited passage is section 413b, which deals with presidential approval and reporting of “covert actions.” In essence, this statute gives the president authority, with a proper “finding,” to send U.S. special forces on paramilitary operations, under command of the CIA. The best-known example was the 2011 raid on Abbottabad, Pakistan, that killed Osama bin Laden.

Talking with U.S. and foreign military experts over the past week, I’ve heard two consistent themes: First, the campaign against the Islamic State will require close-in American training and assistance for ground forces, in addition to U.S. air power; and, second, the best way to provide this assistance may be under the command of the Ground Branch of the CIA’s Special Activities Division, which traditionally oversees such paramilitary operations.

There are some obvious drawbacks with this approach: These “special activities” may be called covert, but their provenance will be obvious, especially to the enemy; they will build irregular forces in Iraq and Syria that may subvert those countries’ return to a stable, transparent system of governance and military operations; and history tells us (from Vietnam to Central America to the Middle East) that black operations, outside normal military channels, can get ugly — opening a back door to torture, rendition and assassination.

Though these paramilitary operations are rarely discussed, the U.S. has extensive experience with them, especially in Iraq and other areas of the Middle East. The 2001 campaign to topple the Taliban in Afghanistan was led by the CIA, using teams of special operations forces to mobilize fighters from the Northern Alliance. In 2002, before the invasion of Iraq, Kurdish special forces were brought to a base in the Western U.S. and trained in insurgency tactics. They conducted fierce attacks as the war was beginning.

To undermine the Islamic State, the U.S. and its allies must mobilize Sunni tribal fighters. The CIA and the U.S. military have considerable experience here, painfully learned from their efforts to combat the Sunni insurgency that arose after the 2003 Iraq invasion. The agency mobilized Sunni commandos known as the UTPs; the initials stood for “Under the Table Program.” The head of Iraqi intelligence, Gen. Mohammed Shahwani, also recruited an irregular Sunni force, which came to be known as the “Shahwani Brigades.” These Sunni commandos fought with the U.S. Marines in the battle of Fallujah in late 2004.

The Islamic State’s commanders know that these Sunni fighters pose a potent threat. Before moving into northern Iraq last spring to prepare their breakout offensive in Mosul, they assassinated former Republican Guard officers who had worked with the U.S. But that only deepened many Sunnis’ secret hatred of the jihadists.

Gen. John Allen, the retired Marine general tapped as Obama’s special envoy in combating the Islamic State, brings several advantages. He coordinated contacts with Sunni tribal leaders in Anbar during the Sunni Awakening, which crushed the insurgency there. He was also one of the most effective U.S. commanders in Afghanistan. In recent weeks, he has been contacted by Iraqi and Syrian Sunni leaders who want U.S. help.

Iraqis and Syrians tell me that U.S. special forces will be decisive in training the Sunni fighters who can carry the battle into the streets of Mosul, Fallujah and Raqqah. Obama must decide whether this mission is better performed overtly or covertly — but the Americans who will be doing the training will be the same warriors, drawn from such units as the Army’s 5th Special Forces Group.

The decisive issue is whether these U.S. special forces should be embedded with the Iraqi and Syrian forces they train — and accompany them into battle, where they can coordinate tactics and call in air support. Gen. Martin Dempsey, chairman of the joints chiefs of staff, said in congressional testimony Tuesday that “where I believe our advisors should accompany Iraqi troops on attacks against specific [Islamic State] targets, I will recommend that to the president.”

Let’s be honest: U.S. boots are already on the ground, and more are coming. The question is whether Obama will decide to say so publicly, or remain in his preferred role as covert commander in chief.