Two airstrikes — one by the coalition fighting the Islamic State group misdirected against a Syrian Army unit, and another apparently by Russian military air against a United Nations humanitarian relief convoy — seem to have shattered the prospects for a cessation of hostilities and joint American-Russian targeting of armed extremists.

The clear winners of this diplomatic unraveling are the extremists themselves and their symbiotic partner in the destruction of Syria and the murderous dispersal of Syrians: the regime of Syrian President Bashar Assad. The obvious losers are Syrian civilians. They will likely remain the principal targets of the Assad regime, Russia, Iran, ISIS and the terrorist band formerly known as the Nusra Front. And nothing politically good can or will unfold in Syria while civilians occupy the bull's-eye.

US Secretary of State John Kerry’s search for common ground with Moscow has had no shortage of critics, including this writer. The prospect of military collaboration between American and Russian militaries in Syria is troubling given the track record of Russian aerial assets, whose appetite for engaging civilian medical facilities is particularly appalling. The absence of consequences for noncompliance by the Assad regime with American-Russian undertakings is telling. The piling of risk onto the backs of Syrian rebels disposed to cooperate with the US is unworthy. Yet the undertaking has had one central merit: It aims to end mass homicide and collective punishment in western Syria, the overwhelming bulk of which is the work of the Assad regime and its two principal enablers: Russia and Iran.

Kerry has been fixated on several indisputable facts. First, the civilian-centric war of the Assad regime has created a humanitarian abomination nearly indescribable in its horror. Second, the abomination has had dire consequences for American friends and allies in the region and beyond, spawning (among other things) a migrant crisis roiling the politics of Western Europe in ways Moscow finds pleasing. Third, mass homicide forms the core of the Assad regime’s political survival strategy: The regime was deeply alarmed when a cessation of hostilities seemed to be working in late February and early March of this year. And fourth, the industrial-strength targeting of civilians in their markets, mosques, hospitals and homes has produced a recruiting bonanza for ISIS and other al-Qaida-related or -descended entities.

Kerry has, at least, tried to address the center of gravity in Syria’s agonizing downward spiral: the protection of civilians.

If the initiative dies, the choice for American policy is stark: go to a real Plan B challenging the Assad mass-murder free ride, or fall back on the arm’s-length observer approach to slaughter in Syria that has produced unintended, negative policy consequences across the board. Kerry’s recent statement to National Public Radio about the only alternative to his initiative being resumption of official American passivity in the face of civilian mass casualties was ill-advised, but chillingly likely to be true. Passivity — at least in a meaningful, operational sense — has been the hallmark of the Obama administration's policy for five years. Unless US President Barack Obama changes his approach and materially challenges the Assad regime’s cost-free campaign of mass homicide, how can the alternative to Kerry’s initiative be anything other than that described by America’s chief diplomat?

John Kerry deserves a chance to resurrect the prospect of a real ceasefire. Without leverage — without the ability to share a credible "or else" with his Russian counterpart — his odds of success are not good. But if the alternative is: "we sit there and do nothing" — as Kerry told radio listeners — then Godspeed, John Kerry.

If, on the other hand, the American commander in chief determines that the wholesale slaughter of civilians by the Assad regime runs counter to the interests of the US and its allies, he will direct his defense secretary to produce options to exact a price. This is not about invasion and occupation. It is not about protecting everyone in all places at all times. It is about confronting physical and moral cowards with cost.

Speaking to the UN Security Council on Sept. 21, a clearly distressed Kerry said the following: "So I want to emphasize this, and I emphasize this to Russia: The United States continues to believe there is a way forward that, although rocky and difficult and uncertain, can provide the most viable path out of the carnage. Our shared task here is to find a way to use the tools of diplomacy to make that happen, and that’s exactly what we’ve been trying to accomplish."

The tools employed by John Kerry to date have been those of energy, persistence, and charisma. They are, considering the nature of those for whom civilian slaughter is as natural as breathing in and out, insufficient. Arthur Miller would have described him as "a man way out there in the blue, riding on a smile and a shoeshine." He deserves a better toolkit from his Oval Office boss.

Frederic C. Hof, director at the Atlantic Council's Rafik Hariri Center for the Middle East, served as a special adviser for transition in Syria at the US State Department in 2012.