Reading - and watching - the news out of Syria, it is difficult for observers to find grounds for optimism. The “peace talks” hosted by the United Nations collapsed in Geneva before they ever reached takeoff speed. The “cessation of hostilities” agreement negotiated between the United States and Russia that went into effect February 27 is riddled with loopholes, and violations have been alleged almost daily. If Russia’s continued bombardment of the anti-Assad opposition under the guise of counterterrorism is any indication, the truce will break down sooner rather than later.

The reason has been well explained by Laurent Fabius, the French Minister of Foreign Affairs: “There can’t be a political negotiation when one side is murdering the other.”

That is certainly an apt characterization of the state of affairs in Syria today.

Nowhere is this more apparent than in the ancient city of Aleppo, once home to more than two million people and currently at the forefront of the battle between the Assad regime and its moderate opposition. Renowned as a stronghold for fractious but non-jihadist rebels, Aleppo, about 60 miles from the Turkish border, has been contested terrain since 2012. In 2014, a broad array of rebel groups associated with the Free Syrian Army joined forces to rid the city of ISIS fighters, but now it is almost entirely encircled by Assad's forces, bolstered by the Iranian Quds Force, Iraqi Shiite militias, and Hezbollah. Overhead, the Russian air force hit supply lines to the city and its civilian infrastructure, including hospitals and schools.

A narrow corridor remains open for residents of the besieged city to escape to safety, and 70,000 people fled prior to the announcement of the cease fire. Turkey, however, has sealed its border after already accepting more than two million Syrian refugees during the past five years of strife. The undermanned and ill-equipped Free Syrian Army still controlled and defended the eastern half of Aleppo, while the regime continued to tighten the noose.

The city’s strangulation will continue apace without a credible threat of force from U.S. and NATO forces, which almost certainly isn’t in the offing, or unless the ceasefire takes hold and leads to serious political negotiations. Even if the ceasefire collapses and pro-government forces drive rebels from Aleppo, it does not mean that Assad will succeed in his declared ambition to reclaim control over the whole of Syria. That possibility still looks remote, so long as ISIS maintains control over a vast stretch of territory from eastern Syria to western Iraq. (ISIS’s position is reasonably secure given that the coalition against it seems content to wage a battle of attrition, hemming in the jihadist army at the margins but not attacking its strategic reserves.)

What is conceivable is that, after years of international demands for a political transition in Syria, the Assad regime will manage to cling to power. The official U.S. demand in August 2011 that Assad “step aside” was effectively disowned when Secretary Kerry admitted recently that an interim government might have a place for Mr. Assad.

The offensive in the outskirts of Aleppo demonstrates the sound rule that political leverage generally follows battlefield success. In other words, as a senior U.S. security official recently admitted to the New York Times, a military solution to the Syria crisis is at hand. It’s “just not our military solution.” The military solution, so long shunned by the West, is being supplied instead by the Russian-Iranian-Syrian-Hezbollah axis.