In the late summer of 2011, President Barack Obama declared the reign of Bashar al-Assad “illegitimate” and told him the time had come to “step aside.” In the early fall of 2015, U.S. officials laughingly dismissed Vladimir Putin’s unexpected direct military intervention into Syria as an accident waiting to happen at Russia’s expense.

Today, Secretary of State John Kerry formally legitimized Assad’s military by way of delimiting its zone of combat; and he welcomed the Russian Air Force as a prospective U.S. partner prosecuting an increasingly complex and muddled war against the so-called Islamic State and al-Qaeda, two separate and competitive terrorist organizations in Syria. Significantly, the latter group often intermingles with U.S.-backed insurgents.

In a tardy press conference in Geneva that most reporters were so sure would never happen they began ordering champagne and pizza, Kerry mapped out this fingers-crossed bilateral plan of action. His remarks were leavened with repeated qualifications and conditional tenses as he described an agreement that must perforce be founded on trust between the United States and Russia would not in fact be based on anything of the sort.

“If, and again I want to emphasize the if —” Kerry began his presser tonight, “If the plan is implemented in good faith, if the stakeholders do the things that are available to them to do and are being called on them to do, this can be a moment where the multilateral efforts at the diplomatic table… could take hold and you could really provide the people of Syria with a transition.”

Except that nobody really believes that.

According to Robert Ford, the former U.S. ambassador to Damascus who resigned from Kerry’s State Department in disgust at the Obama administration’s Syria policy, “Reduced hostilities, if they last, will ease the human suffering, and that’s a good thing. There is not, however, any visible road forward to a political deal that would resolve in an enduring manner the root causes of the Syrian crisis.”

And whatever may be good from this deal is by no means sure to come about.

The Assad regime, Kerry said, will be prohibited from flying combat missions “anywhere where the [Syrian] opposition is present in an area where we have agreed on with any real specificity.” But he did not specify what constitutes the large and ideologically variegated Syrian opposition except to say that it did not include ISIS or the al-Qaeda faction Jabhat al-Nusra, now rebranded as Jabhat Fateh al-Sham.

Noting that indiscriminate and devastating Syrian Air Force raids pursued for years under the pretext of hitting Nusra have only swelled the ranks of the jihadists, Kerry seemed to suggest that precision strikes would somehow do the opposite. He also insisted that any “legitimate” opposition forces must “distance themselves in every way possible from Nusra and [ISIS]” to retain their legitimacy, a contingency that even the smartest of smart bombs is unlikely to facilitate.

“I can’t see enough of the armed opposition de-coupling themselves from front-lines on which Nusra is present,” Charles Lister, author of The Syrian Jihad and a close monitor of the civil war, told The Daily Beast. “There are just too many risks for such a move and they have no previous proof of regime willingness to comply on such restrictions. Nusra will do all they can now to convince opposition factions that this is merely a conspiracy to undermine the revolution. I fear that’s something that many on the ground will buy hook, line and sinker.”

Also problematic is Kerry’s verbose qualification that Assad is only banned from bombing where the U.S. and Russia have jointly determined. This is a rather sneaky way of saying what a draft text of this agreement, which was leaked weeks ago, already stated in no uncertain terms, namely that Assad can deploy his warplanes (PDF) “outside of designated areas if Nusra acquires territory there” and “Russia can use airpower in defense of Syrian government forces in the event of attack by Nusra from within a designated area, if agreed in advance with the United States.”

Assad and Russia can even bomb Nusra in places without prior U.S. consent if “imminent threats” by the group make such consent “infeasible.” But then what is to stop Damascus and Moscow from suddenly finding “imminent threats” everywhere against parties they insist are Nusra or Nusra-affiliated before Washington can concur?

For almost six years, Assad and his surrogates have claimed that the regime is exclusively at war with some shade of “al-Qaeda,” while Putin has insisted since September 2015 that he has been mainly striking ISIS, against all empirical evidence and Pentagon assessments to the contrary.

“If the Russians do as they did last time, a cessation of hostilities was attempted and continue to bomb the anti-regime rebels—under the guise that are in fact ‘terrorists’—this thing will fall apart in short order,” said retired U.S. Air Force Col. Rick Francona, formerly the air attaché stationed in the U.S. Embassy in Syria.

Not that the White House is leaping straight into bed with the Kremlin just yet. A “sustained period” of “reduced” violence in Syria is the litmus test for joint U.S.-Russian airstrikes, Kerry stipulated. Except that this period isn’t going to be very sustained; it will last for just seven days, beginning on September 12, the second day of the Muslim holiday of Eid al-Adha, and it must include all armed groups in Syria, excluding Nusra and ISIS. Those groups presumably will be doing all they can to keep hostilities from abating, and they’ll most likely continue to be bombed.

During this Eid interregnum, two quarters in besieged Aleppo are supposed to feel immediate effects. One is the Castello Road, a main artery for human, commercial, military and humanitarian traffic in Syria’s northern province. Kerry mistakenly said it currently is blocked by two sides.

In fact, three “sides”—broadly speaking—are contesting that road: forces loyal to the Assad regime, the Syrian rebels of various loyalties, and the U.S.-backed Kurdish militias known as the People’s Defense Units, or YPG. All have fought one another at one point and will now be asked to stop doing so as the thoroughfare is turned into what Kerry termed a “demilitarized zone.”

Furthermore, the Ramouseh Gap, a strategically important sliver of territory in Aleppo City, which has changed hands three times in the last several weeks and is now under renewed regime control, will see unprecedented levels of cooperation as both the regime and opposition (which, awkwardly, is here led by Nusra and allied jihadist factions), must now provide “safe, unhindered and sustainable humanitarian and commercial access to eastern and western Aleppo.”

There can be no attacks or retaking of territory in the Ramouseh Gap, even as the skies above (ideally) remain clear of barrel and incendiary bombs for a week and even as Nusra was planning a major counteroffensive to re-break the siege there.

“Will they just cancel these plans and abide by all of this?” Lister asked.

Finally, Kerry announced, if everything goes swimmingly, on September 12 preparations for setting up a Joint Implementation Center, or JIC, will commence with the hosting of initial discussions on what Syrian territories are currently held by Nusra and opposition groups, and the outcome of this discussions will then be vetted and certified by as-yet-unnamed U.S. and Russian experts.

Two experts I would not recommend for the job are Mikhail Khodarenok, a retired Russian Air Force colonel, and Washington, D.C.-based Syria watcher Tobias Schneider, both of whom this week offered withering indictments of the Syrian regime’s military capability and the dependability. The questioned whether the atomized armies doing the heavy lifting for Assad will answer to the president’s commands.

”The regime’s force structure today is not entirely different from that of opposition militias,” Schneider wrote in an article for the website War on the Rocks. “While much better supplied by the Syria Arab Army’s still-standing logistics skeleton, the government’s fighting force today consists of a dizzying array of hyper-local militias aligned with various factions, domestic and foreign sponsors, and local warlords.”

They traffic in weapons, people, and oil to ISIS and rebel groups—the very element with which they’re meant to be in existential conflict—and they also regularly clash with Syrian security forces with impunity because, as Schneider writes, “there is no force loyal to Damascus today that is strong enough bring these brigands in line.”

Khodarenok is even less optimistic about Assad’s chances for fighting real or imaginary terrorists and controlling his infinite proxies.

In an article published in the pro-Kremlin Russian outlet Gazeta, he concluded that “while militias, Iranian volunteers, Hezbollah and [Popular Mobilization Committees] fight in lieu of the Syrian army, Bashar Assad’s soldiers busy themselves with collecting bribes at checkpoints.”

Assad’s conventional army, which Khodarenok believes might be better off disbanded in favor of recruiting a wholly new one, hasn’t waged a “single successful offensive” in a year. “The country’s air force is worn down and uses home-made bombs, the soldiers dig moats to protect from terrorists’ tunnels, while the militants enjoy tactical and moral superiority.” Nor can Russia do much to control the ragtag paramilitaries because “Hezbollah and the Iranians have their own interests.”

All of which is to say that getting the U.S.-backed Free Syrian Army and dozens of non-designated Islamist rebels to rid themselves of any association with al-Qaeda and not fire a shot on September 12 or afterward without prior American approval might actually be the easy part of Kerry’s latest Hail Mary diplomacy. There’s no guarantee that Putin and Assad can, even if they want to, deliver on their end of the bargain.