The top U.S. general in Iraq said Monday that more American troops on the ground may be needed to help the Iraqi army mount the kind of conventional warfare operations needed to defeat Islamic State militants.

"Yes, there is a good potential that we will need additional capabilities, additional forces to provide those capabilities. And we're looking at the right mix … in consultation with the government of Iraq and our other partners," Army Lt. Gen. Sean MacFarland told reporters Monday.

The general said the American-led military training mission there is now focused more on conventional warfare tactics. "We have shifted from a pure counterinsurgency focus and are now preparing the [Iraqi security forces] to conduct what we refer to as combined arms operations," MacFarland said in a video teleconference from Iraq.

"The ability to integrate infantry, armor, artillery, air power, engineers and other assets on the battlefield, provides the Iraqis with a decisive advantage over a static enemy dug in behind complex obstacle belts," MacFarland said.

"I've been directed to come up with a series of proposals. Some would call them 'accelerants' to the campaign that would allow us to increase the pressure on the enemy. Now, that doesn't necessarily equate to boots on the ground. It doesn't necessarily equate to American boots on the ground. It could be coalition boots on the ground. It could be a capability that doesn't require any significant number of troops on the ground," MacFarland said.

When reporters repeatedly asked about the prospect of American troops participating in combat operations, the general did not rule anything out. "The decision as to whether or not … something is on or off the table is not my decision. That's really, at the end of the day, that's my commander in chief's. So, you know, all of us in uniform are … preparing various options. The president will decide," MacFarland said.

There are about 3,700 U.S. troops in Iraq who provide training for the Iraqi security forces and sometimes accompany them to forward positions to support Iraqi-led combat operations.

MacFarland's comments came as a top White House official was wrapping up a rare trip to Baghdad to meet with Iraqis about the next phase of the fight against the Islamic State, also known as ISIS or ISIL. Special Presidential Envoy Brett McGurk arrived on Saturday and departed Monday, officials said.

In December, Defense Secretary Ash Carter said that the U.S. was willing to deploy American pilots with Apache combat helicopters to Iraq to provide better close-air support. Carter also said the U.S. could send more combat "advisers" to embed with Iraqi forces at brigade-level headquarters.

Yet the Iraqis declined that new level of U.S. support for the Battle of Ramadi in late December. Many experts say that reflected the influence of pro-Iranian factions inside the Baghdad government who oppose any expansion of the U.S. military mission.

MacFarland downplayed the Iraqis' decision and said the offer remains on the table.

"We're not rebuffed or anything like that," MacFarland said. "The prime minister didn't actually turn it down flat. What he said was, you know, 'Around Ramadi, things seem to be going in a pretty good direction. I'm not sure I need it right here, right now.' But he didn't say no. He said, you know, maybe a little bit down the road we'll need it for other places in Iraq."

MacFarland said the current mission in Iraq is fundamentally different from the war following the 2003 U.S. invasion. "There's a dynamic here that really we didn't have during Operation Iraqi Freedom, which is everything that we do is by, with and through a partner force on the ground," MacFarland said.

U.S. and Iraqi forces are focused on pushing the Islamic State militants, also known as ISIS or ISIL, out of their two key strongholds, Mosul in Iraq and Raqqah, Syria.

For now, ISIS is "really more of a conventional force," MacFarland said.

But that could change.

"Will the enemy revert to some sort of insurgency? A low-grade insurgency or back to a terrorist organization and be able to do spectacular attacks or limited operations in Iraq? That's a possibility and we will ensure that the holding force that is in Iraq is sufficient … to deter or defeat those types of attacks or respond to them, should they occur," MacFarland said.