Sen. Tim Kaine (D., Va.), considered to be on Hillary Clinton’s shortlist for potential running mate consideration, applauded Sen. John McCain’s (R., Ariz.) grilling of Defense Secretary Ash Carter in a Senate Armed Services Committee hearing on the Islamic State terrorist group.

"Senator McCain is exactly right and he's been making that point since last September, saying if we're going to train folks to fight ISIS in Syria, what if they get attacked by the Assad regime, and he has yet to get a clear answer," Kaine said Wednesday on Morning Joe.

McCain’s tough line of questioning on Tuesday focused on the current policy of the Obama administration to only train Syrian fighters if they agree they will only engage terrorist extremists, and not combat the embattled Bashar al-Assad regime. The policy has drawn criticism because U.S. forces have trained only 60 Syrian rebel fighters, 1 percent of the goal the Pentagon has set.

McCain pointed out that the Defense Department has yet to offer any guidelines for the rebels in case they are attacked by Assad forces. Carter, startled by McCain’s anger on the issue, said the United States would look into the policy.

"[McCain is] absolutely right," Kaine said. "We can't insert and train fighters back into that theater without giving them protection if the Assad regime attacks them. He was right to make that point. 60 trainers is way too small."

Carter agreed with McCain that 60 total fighters trained is unacceptable.

"I said the number 60, and I can look out at your faces and you have the same reaction I do, which is that that's an awfully small number," Carter said at the hearing on Tuesday.

The Pentagon says it is currently vetting 7,000 volunteers in Syria and hopes to train up to 5,000 fighters by the end of the year. A Washington Free Beacon analysis found that with over half the year already passed, the Pentagon still has 4,940 Syrian rebel fighters left to reach their goal.