The agreement made last Saturday by the United States and Russia to eliminate Syria's arsenal of chemical weapons is not so unusual.
Two decades ago, during Yugoslavia's civil wars, diplomats in Moscow and Washington frequently concluded disarmament deals only to see these ignored even before the ink was dry on the documents. And the same may happen with this latest Syrian agreement.
Nevertheless, the deal is unique in both purpose and potential impact. Regardless of whether it succeeds or fails in its objective of disarming Syria, this document will define US President Barack Obama's foreign policy from now until the day he leaves the White House in early 2017. The stakes could not be any higher.
The temptation among commentators and diplomats is to assume that the US-Russia deal over Syria must have been hatched in secret talks over a longer period of time. After all, that's the story of most deals between these two former Cold War opponents. But the truth on this occasion is more boring: The deal is a haphazard arrangement intended to paper over botched policies in both Russia and the US and seized by both sides because both are actually weaker than either would care to admit.
President Obama's difficulties with persuading the US Congress to back a military intervention against Syria's chemical weapons dumps are well known, so Washington's eagerness to sign a deal which promises to achieve the same thing without firing a shot is understandable.
But Russian President Vladimir Putin is also in a similar bind. He knows that his vetoes in the United Nations Security Council will not prevent a US military operation against Syria.
He also knows that once such an operation has begun, Russia would be powerless to affect its outcome. In addition, the US military would have made mincemeat of the air defence systems which Syria bought from Russia, so the macho-strutting, judo-loving Mr Putin would have been served with a further humiliating reminder of just how technologically backward his country really is.
For all these reasons, the Russians also needed a deal which averted a military showdown.
Few compromises made
Predictably, the agreement consists of compromises by both sides, although a closer reading of the text indicates that neither Russia nor the US have made any serious concessions. The Americans have given up their threat of immediate military action. But as Mr Obama has subsequently explained, "if diplomacy fails, the US remains prepared to act".
The Russians, in turn, won the right to lead diplomatic efforts but in exchange had to accept that if these fail, the Syrian dossier will return to the United Nations Security Council "under Chapter VII of the UN Charter" - traditional code words for the internationally sanctioned use of force against an offending state.
Yet that's less of a concession than it appears, partly because Russia retains the right to veto any resolution and also because Chapter VII of the UN Charter explicitly mentions many other "measures not involving the use of force". So Russia can still deprive the Americans of an opportunity to get UN backing for any military operation. In short, this is more of an agreement to disagree, rather than a pact between diplomats who see eye to eye.
Can it be made to work? The technical difficulties are considerable. The underlining assumption of the entire deal is that Russia exercises sufficient control over Syrian President Bashar al-Assad to force him to give up his chemical weapons. But that's a tall order since Syria's chemical capabilities were developed not as an instrument of internal control but as a deterrent against Israel's nuclear arsenal - giving them up will alter the Middle East's strategic balance.
Mr Assad may also not be particularly impressed with the argument that giving up his chemical capability is the only way to ensure his survival. He may recall the fate of Muammar Gaddafi, the Libyan leader who was first persuaded to give up his arsenal of weapons of mass destruction, only to then be rewarded for his cooperation by being bombed out of existence by the US-led Nato alliance.
Even if Mr Assad cooperates, there will be disputes about the list of his nuclear weapons facilities which he has to submit within a week. Nobody knows how an international team of inspectors will be put together, what mandate it will have, whether the UN will be given control over this operation, and whether the chemical inspectors would require military protection, precisely those "boots on the ground" which everyone currently rules out.
The proposed timetable for the operation, which envisages that all Syrian chemical weapons be dismantled or destroyed by the middle of next year, is hopelessly optimistic.
Neither the US nor Russia, which are engaged in destroying their own chemical arsenals, have met even one of their self-imposed disarmament deadlines over the past two decades.
Still, the technical difficulties should not be exaggerated. Both the US and Russia know a great deal about the size of Syria's chemical arsenal. The Russian military also has a great deal of experience in evacuating chemical dumps in a great hurry. After all, that is what it did as the Soviet Union collapsed in 1991.
There are also short-term measures which can ensure that Syria is deprived of its chemical capabilities: The country's stocks of mustard gas - which are probably too dangerous to move - can simply be kept under foreign control, while the stocks of sarin and other nerve gases built into weapon delivery systems can be quickly airlifted out of the country. So if the will is there, technical means can be found.
The biggest problem is the impact of this deal on the United States' global standing. US officials are right to claim that, had it not been for Washington's threat to use force, the deal would never have come about.
But the agreement is universally seen as a triumph for Russia, for it comes after a series of goofy diplomatic moves by Washington. A US President who did nothing about a Syrian civil war which has lasted for more than two years and already killed at least 100,000 people suddenly decided to act, but then had second thoughts and asked Congress for its opinion while also asserting that he did not really need congressional approval.
And, just as bizarrely, while President Obama warned ominously that once engaged the US military doesn't do "pinpricks", his Secretary of State told everyone that what was being planned in Syria was an "unbelievably small" operation. Would "pinstick" be a better term, then? Predictably, an unbelievably small commitment has resulted in a puny reputation. It's difficult to see how Washington can derive any credibility out of the current deal over Syria.
For the deal to be respected and implemented, the US will have to accept that Mr Assad remains in power. Indeed, the Americans may soon be asked to stop supplying weapons to the rebels if they wish to see international chemical inspectors enter the country.
But that would reinforce the image which the US already has in the Middle East as a fickle, fair-weather friend. While the Russians defend their allies, the Americans dump theirs whenever it suits Washington, at a moment's notice.
US in a tight corner
If the US-Russian deal fails, the Americans will still be faced with equally unpalatable choices. Mr Obama will still have to convince Congress not only about the use of force, but also why he trusted Russia and Mr Assad in the first place. Even if he gets congressional support, Mr Obama will never be able to shake off his image as a reluctant warrior, a leader who did not know how to exercise the considerable military power at his disposal.
Precisely because these pitfalls are already known in Washington, it is likely that the real problem with the deal over Syria is not whether its provisions will be respected by the Syrian government but, rather, how many concessions the US is prepared to make in allowing diplomatic efforts to continue.
The answer must be that US patience is very limited, for Mr Obama knows that if the deal succeeds in disarming Syria he may not get much credit for this. But if it fails and the US does nothing, he will be accused of allowing the US to be tricked by Russia into a fake arrangement which provided neither peace nor honour. And that, in turn, will mark the remainder of his presidency just as surely as it did that of Jimmy Carter's during the 1970s.
But nobody should underestimate the US' ability to escape from tight corners. As Britain's war-time leader, Sir Winston Churchill, once shrewdly remarked: "The Americans can always be counted on to do the right thing, after they've exhausted all other possibilities."
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