President Barack Obama’s plan to send an additional 450 to 500 troops to Iraq’s Anbar province won’t be his last word on the crisis posed by the Islamic State in Iraq and the Levant (ISIL), several senior serving and retired U.S. military officers believe. Turning the tide against ISIL in Iraq will require a more robust U.S. military commitment, with options for escalation a matter of lively debate.

Obama on Tuesday announced that the additional troops would be deployed to train units of the Iraq Security Force (ISF), which Defense Secretary Ashton Carter said “showed no will to fight” to prevent the city of Ramadi from falling to ISIL. The administration also hoped those troops could provide a bridge to Anbar’s Sunni militias, which had initially fought the U.S. occupation, then after 2006 sided with the U.S. against Al-Qaeda, but had been alienated by the Shia-led government in Baghdad. The new training commitment would bring the total number of U.S. troops in Iraq to just over 3,500.

That won’t change the equation, one senior officer, speaking on condition of anonymity, told me following Obama’s announcement. “There’s a growing awareness that the program to train and equip [the Iraqi army] just isn’t going to work, and that the U.S. is going to have to do a lot more. Obama doesn’t want to admit it, but I think everything is on the table.”

This senior officer added that there are three options for escalation currently under discussion at the Pentagon: embedding U.S. troops in Iraqi units to strengthen them; expanding the air war against ISIL command, control and resource targets; and deploying U.S. ground forces on a combat mission to defeat ISIL in Anbar.

The embedding option is favored by a small, but vocal group of former officers who served in Anbar during the years of the Awakening movement, when U.S. forces forged an alliance with Sunni tribes that had turned on Al-Qaeda. One of these officers is retired Col. Peter Mansoor, who served as a key adviser to the U.S. commander in Iraq, Gen. David Petraeus, from 2007 to 2008. The fall of Ramadi, Mansoor has written, means that the U.S. will need to send in more military advisers and trainers, and that “we are going to have to accompany Iraqi forces into combat.” Another former officer, retired Lt. Col. John Nagl, agrees, saying the street-by-street fighting in Anbar must be done by Iraqi soldiers “with American advisers in close support.”

Senior Marine veterans of Anbar also favor the embedding option. One of these Marines, speaking on condition of anonymity, said embedding even a small number of U.S. special forces trainers in ISF units — “four or five for every Iraqi battalion ought to do it,” he said — would make a huge difference. That view was echoed by a retired U.S. Army Brigadier General who served in Baghdad. He told me that “putting even a small number of [U.S.] advisers inside of ISF units would significantly strengthen the Iraqi army’s ability to fight ISIL. We would provide the leadership and direction they lack.”

Describing such a deployment option as a “white” special forces program (as opposed to a “black” one, which would put U.S. troops in direct combat roles), this former Army officer says that such a decision would “add steel to Iraqi formations” and “allow for more direct fire support from U.S. aircraft” during anti-ISIL operations. Boosting the ISF in this way, he argues, would also provide a capable Iraqi alternative to the Iran-backed Shia militias in the fight against ISIL.

The embedding option also appeals to Anbar’s tribal leaders, who have appealed for more direct U.S. help. Interviewed by phone last week, a senior Anbar tribal leader said the situation in Ramadi was “desperate,” and “approaching anarchy.” He confirmed that Anbar’s most important tribal officials had been able to escape Ramadi prior to the ISIL takeover on May 16. He reiterated complaints that the Iraqi government was “corrupt,” and “in the pocket of the Iranians.” This leader, who also spoke on condition of anonymity, remains skeptical that the additional trainers announced Tuesday by the Obama administration will make a significant difference. “It’s not only going to take more than that,” he said, “he really didn’t say what he was going to do to help us. The Sunni militias are the key to retaking Anbar, not the Iraqi military.”

A second option, favored by a growing number of Air Force officers, would be to escalate U.S. air strikes to cover urban areas held by ISIL, where they would risk inflicting higher civilian casualties. They argue that the current program of air strikes focused on ISIL’s frontline forces is failing to erode its military capacity. “We have to have an air campaign that is a thunderstorm, not a drizzle,” retired Air Force Lt. Gen. David Deptula told me, arguing that the U.S. could do far more to degrade ISIL’s capacity to control conquered territory without having to place U.S. boots on the ground. “Why is the road between Raqqa [in Syria] and Mosul, for example, still open?” Deptula said recently. “Why is electricity in [Raqaa and Mosul] not terminated?”

Deptula is quick to counter suggestions that U.S. airstrikes in urban areas controlled by ISIL would be inhumane. “This is one of the problems,” he said. “There’s been more attention to the avoidance of collateral damage and civilian casualties than there has been to the accomplishment of eliminating ISIL.” Deptula’s moral argument against the U.S. allowing ISIL to control large population centers resonate with many in the military.