"I wish the president had said what he told Lindsey Graham and me in the Oval Office," Sen. John McCain (R-Ariz.) said at a Wall Street Journal breakfast this morning. "That he would support efforts to help the Free Syrian Army change the momentum and that would lead to negotiations that would lead to the departure of Bashar al-Assad."

Sen. John McCain (R-Ariz.) Menahem Kahanamenahem/AFP

But Obama didn't mention helping the Free Syrian Army, and he's currently involved in negotiations that would probably make it impossible for him to really help the Free Syrian Army.

McCain's comments are a reminder that President Obama has articulated two strategic objectives on Syria -- and those objectives are now coming into direct conflict.

The first objective, which formed the core of Tuesday's presidential address and most of the administration's public strategy, is to reinforce the international ban on chemical weapons. The second -- which, as McCain notes, is emphasized more often behind closed doors and less often in public -- is to hurt Assad badly enough that he decides to negotiate some kind of power transition, but not so badly that his regime collapses.

It's never been clear exactly how the United States weights these two objectives. It has occasionally seemed that the proposed strikes to punish Assad for his alleged use of chemical weapons were cover for strikes that were actually designed to weaken him militarily. At other times, it's seemed that the administration's interest in undermining Assad is simply a lure to win the support of hawks like McCain for limited strikes that would reinforce the prohibition on chemical weapons but leave Assad's position largely unchanged.

This ambiguity provides a clue to why Russia and Syria are proposing a disarmament plan in the first place: They're forcing the Obama administration to actually choose between these two objectives -- and to choose the one that poses far less of a long-term threat to Assad's and Putin's interests.

McCain noted that even as negotiations over the disarmament proposal ramp up, Assad has "resumed air attacks on the Free Syrian Army and stepped up ground attacks against the rebels. He basically feels he has kind of a free ride, at least for a period of time."

The reasoning is simple, and probably correct: The United States isn't going to bomb Syria so long as there's an ongoing process to destroy Assad's chemical weapons. And any resolution that Russia and Syria would agree to will, at the very least, require the United States to forswear the use of force against Assad so long as he's fulfilling the terms of the agreement on chemical weapons.

"If you're sitting in Putin's seat, I think you're feeling pretty good today,"  McCain said. "You've delayed the strikes on your ally who you've been supplying. You've played a major role in designing whatever agreement will be sold. And you've made it clear you'll continue to support Bashar al-Assad with weapons and whatever else you can provide him with."

And, though McCain didn't say this, you might be about to get the United States to sign onto a deal that basically guarantees they won't seriously step up their support for Assad's opposition. From the perspective of Russia and Syria, that's the upside of the deal: They give the United States what it wants on chemical weapons, but in return, they get the assurance that Washington won't act to turn the war's momentum against Assad.