The goal is to lay the groundwork for local forces to retake both Raqqa, Syria, and Mosul, Iraq, and eliminate ISIS' ability to use them as areas from which to plan external attacks.
President Barack Obama emphasized the importance of that goal after a meeting with top commanders at the White House earlier this week.
"We should no longer tolerate the kinds of positioning that is enabled by them having headquarters in Raqqa and Mosul. We've got to keep on putting the pressure on them," Obama said Tuesday.
An increased level of special forces is just one of a number of possibilities.
If approved, these troops would grow the current U.S. Special Operations effort of up to 50 troops authorized to be in Syria. They are there to provide advice and assistance to moderate Syrian forces fighting ISIS.
That effort has proven successful in several recent battles, including efforts to cut ISIS travel between Raqqa and Syria and to retake the key town of Shaddadi in Syria.
"We are considering a number of different proposals to accelerate the defeat of ISIL by better enabling local forces, but no decisions have been made," said Navy spokesman Capt. Jeff A. Davis, using a different acronym for the terror group.
U.S. officials had originally told CNN the proposed increase would be just a few dozen because of the need to provide additional support forces such as aviation and intelligence. But another emerging line of thinking is to agree to an overall significant increase, publicly announce it and then send in the forces gradually over time.
As the Pentagon looks at trying to accelerate its campaign against ISIS in Syria and Iraq, the idea of increasing reliance on Special Operations forces is gaining traction, but officials caution a final decision still must be made. A number of options have been presented to the White House.
There will be an increased risk if the number of Special Operations forces rises. Their work is highly dangerous, as they operate in small teams potentially far from their base in northern Syria near the Turkish border.
The number of Special Operations forces inside Syria ebbs and flows, with perhaps less than half the authorized amount inside Syria at any one time, one official said.
The idea being discussed is to add more teams to the effort so perhaps the moderate forces can accelerate their own fighting. But some officials advocate keeping the numbers relatively small so they can maintain a low profile and not require additional transportation and supply support that might become visible.
One of the major tasks ahead is trying to get opposition forces geared up in the coming months to fight to retake Raqqa, ISIS' self-declared capital in Syria. The U.S. hopes Syrian Arab forces, as well as some members of the Syrian Democratic Front, which includes non-Arab fighters, will be in a position to do that with U.S. advice and assistance, the officials said.
The U.S. military has also restarted a small training effort for Syrian anti-ISIS fighters months after an initial effort failed.
The current training program has small numbers of U.S.-selected fighters from various groups, transporting them across the border to Turkey for several days of basic training. The fighters are given radios and taught how to communicate with U.S. forces. When they see potential targets, they inform the U.S., which then sends its own reconnaissance aircraft to determine if the target should be struck.
Options to increase efforts in Iraq may be less dramatic. U.S. officials are trying to see if the Iraqi government would accept additional fire support from either ground-based artillery or Apache helicopters. Additional U.S. trainers are expected to be sent to Iraq, with all of the increases aimed at helping the Iraqi forces prepare to retake Mosul.