Russian President Vladimir Putin in Finland on July 1. (Lehtikuva/Jussi Nukari/Reuters)

FOR SEVERAL years, the Obama administration’s Syria policy has been stuck in a cycle of failure. Secretary of State John F. Kerry negotiates deals with Russia to end the fighting or create a new government in Damascus, while warning that if they are not respected by Russian President Vladi­mir Putin or Syrian President Bashar al-Assad, the United States will consider other options, such as stepping up support for Syrian rebels. In every case, the Russian and Syrian regimes have betrayed their commitments, continuing to bomb civilian areas, employ chemical weapons and deny aid to besieged communities. And no wonder: Each time the U.S. response has been to return to the Russians, offering more concessions and pleading for another deal.

And so it goes again. Senior U.S. officials have publicly confirmed that Syria and Russia have grossly violated a cessation of hostilities negotiated by Mr. Kerry in February. They have continued to attack Western-backed rebels, deliberately targeted hospitals and other civilian infrastructure, and blocked aid convoys to besieged towns where children are starving to death.

Mr. Kerry warned that the consequence of such breaches would be a “Plan B” of stepped-up U.S. support for anti-Assad rebels. Instead, as The Post’s Josh Rogin has reported, the administration delivered a new proposal to Moscow on Monday that offers Mr. Putin what he has been seeking for months: greater U.S.-Russian collaboration in targeting those anti-Assad rebels deemed to be “terrorists.” In exchange, Russia would — again — promise to restrain its own and the Assad regime’s bombing of areas where Western-backed forces are located.

As several experts on Syria told The Post, it is a deal whose only tangible result would likely be the reinforcement of the Assad regime — whose relentless brutality has empowered the Islamic State and al-Qaeda. The U.S.-Russian collaboration would target an offshoot of al-Qaeda called Jabhat al-Nusra, whose forces are fighting the Assad regime in several areas, including the key city of Aleppo.

In practice, the Jabhat al-Nusra forces are intermixed with other rebel units; many Syrian fighters joined the presumed terrorists for practical rather than ideological reasons. An assault on them could have the effect of allowing the Assad regime to achieve what it says is its foremost objective, the recapture of Aleppo, tipping the balance of the civil war in its favor. The anti-Assad rebels backed by the West could be decisively undermined, even if Russia and the Syrian regime respected the no-bombing zones — which, given the history of past agreements, is a most unlikely prospect.

Administration officials claim they have no alternative but to go along with Mr. Putin. The former Plan B, more support for rebels, would merely lead to more fighting with little result, they say. It’s the same logic that President Obama has used to deflect proposals for U.S. action in support of anti-Assad forces since 2012 — even as the country, and the region around it, spiraled deeper and deeper into bloodshed, chaos and humanitarian crisis. Mr. Obama appears fiercely determined to learn nothing from his tragic mistakes in Syria. The latest U.S. proposal, if accepted by Mr. Putin, would compound the damage.