The massacre of more than 100 men, women and children at Houla has buried the peace plan for Syria promoted by former United Nations Secretary General Kofi Annan. Soon, the regime and its opponents will get to fight out their civil war unobstructed.

When that happens, Syria will present the U.S. and Russia with choices that have implications far beyond the fate of a single Middle Eastern dictator, including stronger Russia-China cooperation to counter U.S. foreign policies.

It’s a defining aspect of the Syrian conflict that it has split the international community, especially the U.S. and Russia, making it difficult to force any solution on the warring parties. Americans see Russia as supporting a last, fellow authoritarian ally in the Middle East. Russians retort that U.S. policy toward Syria is all about changing the regime in Damascus, because it’s allied with Tehran, and that the U.S. never tried to make Annan’s peace initiative work.

Each accuses the other of allowing violence in pursuit of larger geopolitical goals, regardless of the human cost. The atrocities at Houla merely raised the temperature of that dispute.

In the days after the massacre, Russia’s President Vladimir Putin made it clear to European counterparts that his opposition to foreign military intervention in Syria was as strong as ever. This has put Russia on a potential collision course with the U.S., should President Barack Obama decide -- against his own best judgment -- to authorize military action in Syria.

Turning Point

That scenario no longer looks as unlikely as it once did. Former U.S. President Bill Clinton has already talked about Obama reaching his Bosnia moment. The U.S. election is mainly about jobs and the economy, but there is only so much passivity that a White House incumbent can afford when faced with an acute humanitarian crisis. Once the Annan plan is pronounced dead, Syria’s civil war will gain in intensity. Arms shipments to the opposition will increase and military advisers from Arab and other countries will probably follow. As the death toll accelerates, calls for international military intervention may become irresistible.

A U.S.-backed military intervention would lead to a deep rupture with the leadership in Moscow. Russia wouldn’t try to stand in the way militarily, but it might well be driven to forge a stronger strategic partnership with China, which also opposes foreign military interventions in the Middle East and has joined Russia in vetoing UN Security Council resolutions on Syria.

China has been ambivalent in the past about Russian overtures to ally against the U.S., but that’s changing due to concerns over the implications of Obama’s pivot to Asia. There have recently been calls from within the Chinese military for an alliance with Russia to stand up to the U.S. pressure. China’s political leadership, for the time being, remains skeptical, and so does Putin. But in Moscow, too, there’s a pro-China lobby, and Western intervention in Syria could provide the catalyst for a strategic rebalancing, with wide-ranging implications for the U.S.

Putin has been in Beijing this week to meet Chinese leaders, including at a summit of the Shanghai Cooperation Organization, a regional security and development arrangement focused on Central Asia. (In a coincidence of scheduling, Hillary Clinton was meeting some of her allies on the Syrian issue in Istanbul at the same time.) How to handle Syria, Iran and the U.S. were topics for discussion in Beijing.

Russia’s Bind

Putin has vowed that Syria will not be another Libya, and it won’t be: Russia will block any UN Security Council resolution that authorizes the use of force in Syria. Nor will Russia support economic sanctions. Yet the Russian government finds itself in a bind. Its calculation that Assad would prevail over the opposition, Bahrain-style, woefully overlooked the external dimension to the Syrian drama. Now it’s accused of protecting the “butcher of Damascus,” while China withdraws into its shell. To the leaders of the Kremlin, this looks unfair.

To start with, Russia doesn’t count Assad as an ally -- he’s merely a business client. Russia did lean on Assad, persuading him to agree first to an Arab League mission, and then the Annan plan. Nevertheless, it’s clear that Putin is losing the argument internationally. Susan Rice, the U.S. ambassador to the UN, hinted after the Houla massacre that the U.S. might go outside the Security Council to take tougher action, thus circumventing the Russian and Chinese vetoes.

What can Russia do? There are just two options. One is to stick to the current approach. This won’t stop foreign involvement outside the UN, nor civil war, but Russia would be able to denounce interference in Syria as illegitimate and watch the resulting mess from the sidelines. That mess would be huge and many outsiders who venture into the Syrian conflict may emerge bruised. Still, Russia would suffer reputational damage and would pay a price for being on the wrong side of history, especially if Assad were to fall.

The alternative would be based on an idea recently invoked by Foreign Minister Sergei Lavrov, namely that in civil conflicts, the incumbent government bears a much larger responsibility than its opponents do. Had he really wanted a peace settlement, Assad might have used Russia to help him arrange for a political transition in Syria. Instead, he used Russia as a cover for stalling on peace and expanding a war against his people. He has therefore failed in his responsibility.

Lavrov and most recently his deputy, Gennady Gatilov, have said they would be willing to accept a solution that involves Assad’s departure, so long as that doesn’t involve a foreign military intervention. This is, potentially, a point of convergence between the U.S. and Russia.

Inviting Blowback

U.S. leaders should hold back from approving any military action. Beyond the many risks on the ground, the U.S. would invite blowback in the form of deeper rifts with Russia and China in priority areas such as pressuring Iran over its nuclear program. China and Russia might also be motivated to overcome their differences and breathe real muscle into the Shanghai Cooperation Organization, turning it into a counterpart to NATO.

Instead, the U.S. should make it clear to Russia that it doesn’t foresee military intervention or forced regime change in Syria, and that it would lean heavily on the opposition in Syria to agree to talks and a political transition with the regime in Damascus, though not with Assad.

Russia, for its part, should tell Assad: Your time is up, we will no longer ship arms to a government involved in a civil war, and the only thing we can do for you now is to help negotiate your safe passage out of the country. Letting go of Assad at this point, while encouraging members of the Syrian military not implicated in atrocities to take over and open talks with the opposition, would not plunge Syria into a civil war -- that has already begun. What it might do is shorten the conflict and save lives. If lives are more important than regimes -- and they are -- then this is the path to follow.

(Dmitri Trenin is director of the Carnegie Moscow Center. The opinions expressed are his own.)

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To contact the writer of this article: Dmitri Trenin at DTrenin@carnegie.ru

To contact the editor responsible for this article: Marc Champion at mchampion7@bloomberg.net