Senior national security officials will meet this week to discuss options for how to revamp the Pentagon program to train and equip moderate Syrian rebels, a senior defense official told CNN. The Pentagon has been reviewing the program for several weeks after the initial group of some 54 rebels put into northern Syria this summer came under attack and are no longer a functioning fighting force. Some of the options being considered include waiting until a larger number of trained rebels finish the program and can be inserted into the area before sending them into combat against ISIS, also known as ISIL, and putting the rebels into more stable combat areas than where the initial group came under attack, the official said. RELATED: U.S. committed to accepting more Syrian refugees The Pentagon is also looking at partnering the rebels with other groups, such as the Kurdish YPG, but that may be problematic because the groups have different agendas. The Pentagon continues to express confidence in the program and a commitment to continuing it. Defense Secretary Ashton Carter “still believes that it’s important to provide support to those moderate Syrian forces,” Pentagon spokesman Peter Cook said Tuesday. “We’re going to continue moving forward with that program.” He called local fighters on the ground “a critical component, maybe the critical component, in ultimately degrading and defeating ISIL.” But he acknowledged the “hard questions” being asked about the program. “We’ve learned lessons from that (and) continue to learn lessons from that,” Cook said. Perhaps the biggest challenge that remains is simply training and fielding enough rebels to make a difference. So far, some 7,300 men have been identified for possible training. Of that group, 2,400 were submitted for formal consideration, but many did not pass the vetting process. The United States wanted to train up to 5,000 rebels in the first year of the program. But so far, the 54 in the first class and approximately 70 in a second class are the only ones known to have been trained. There is a third group of trainees, but the Pentagon is not yet saying how many are in that group. The second and third cohorts are in training, and the Pentagon is working on vetting additional cohorts beyond that. Saudi Arabia, Turkey, Qatar and Jordan have said publicly they will host training. To date, the training has been conducted only in Turkey and Jordan. As of May 30, the Defense Department has spent $41.8 million to fund the training and equipping of the vetted Syrian opposition. No further update is available.