Russian President Vladimir Putin announced a “fragile” Syria cease-fire deal Thursday, saying Russia and Turkey will “guarantee” the truce. But the question is: will the agreement hold up over time?

Stephen Hadley, principal at international consulting firm Rice Hadley Gates and former national security adviser to President George W. Bush, stressed implementation will be “very difficult.”

“The opposition groups that are party to the settlement are a very varied group,” Hadley said Thursday on “CBS This Morning.” “The issue of enforcement is going to be difficult on the opposition groups. Quite frankly, the issue of enforcement is going to be very difficult with the Assad regime, which has a very checkered record in terms of honoring cease-fires.”

Syria’s military said the cease-fire will take effect at midnight local time, and Russia’s defense minister said it would cover 62,000 rebel fighters across Syria. But according to Turkey’s foreign ministry, groups regarded as terror organizations by the U.N. Security Council would be excluded from the deal. That’s an important caveat, reports CBS News correspondent Holly Williams, because it could mean that not only would the Islamic State of Iraq and Syria (ISIS) be excluded from the deal, but also some rebel groups and Kurdish fighters. However successful the cease-fire is when it comes into effect, it will not mean an end to the Syrian civil war, which has been raging for more than five years.

What is interesting in the cease-fire deal that is part of a peace initiative backed by Russia, Turkey and Iran, Hadley said, is that the United States is “noticeably absent.”

“Why? Because the peace is really being driven by those that have made the commitment, that have troops on the ground, and our commitment has been very modest,” Hadley said.

Hadley said Secretary Kerry has made “herculean efforts” to try to negotiate cease-fire in Syria, but has expressed frustration on failed efforts.

“We were not active enough on the ground in going against ISIS and al Qaeda groups, but also being active on the ground to be a check on what Russia and Iran and, in some sense, the Assad regime could do,” Hadley said. “If you’re not on the ground, if you don’t have skin in the game, you’re not going to have much weight at the negotiating table and I’m afraid that’s what we’ve seen here.”

Hadley, who helped President Bush in efforts to broker a two-state peace treaty between Israel and the Palestinians, also discussed Secretary Kerry’s speech Wednesday defending the United States’ decision to abstain on a U.N. Security Council vote condemning Israeli settlement activity.

“Secretary of State Kerry was venting a lot of frustration. He’s had failure to reach a Middle East peace. He believes it’s because the settlement activity, that that settlement activity raises questions about the viability of a two-state solution,” Hadley said.

But Israeli Prime Minister Benjamin Netanyahu “predictably” pushed back, Hadley said, and “basically made the point that it is not settlements that are a barrier to peace but the unwillingness of the Palestinians, in his view, to accept Israeli as a Jewish state in the Middle East.”

According to Hadley, a problem of the Obama administration’s policy is that they haven’t made a distinction between two different settlements.

“There are some settlements that are east of the barrier or the wall that had been constructed in Israel that are on major settlement blocks that even most Palestinians concede will be part of Israel in a final settlement,” Hadley said. “There are then settlements that are on the eastern side of the barrier or the wall on areas that most people rightly think will be part of any Palestinian state once there is an Israeli-Palestinian peace.”

