Secretary of State Hillary Clinton is putting a positive spin on a new peace plan for Syria agreed to last weekend in Geneva by the Syria Action Group, which comprises the permanent members of the United Nations Security Council as well as Turkey and Arab representatives. We hope her optimism is justified, but Russia continues to send maddeningly mixed signals about whether it recognizes that the time has come for Syrian President Bashar Assad to step down.

Already a humanitarian tragedy, the civil war in Syria now threatens to spill into international conflict. Last Sunday, Turkey, a member of NATO, said it had scrambled fighter jets along its border after Syrian helicopters were detected close to Turkish territory. On another front, U.N. Secretary-General Ban Ki-moon has called on Syria to respect its border with Lebanon.

The agreement reached in Geneva does represent movement by Russia and China. In February, both governments vetoed a Security Council resolution that would have called on Assad to step down in favor of his top deputy, in accordance with an Arab League peace plan. The new plan, although it does not call on Assad to step down, calls for a transitional government to be formed “on the basis of mutual consent” of the Assad regime and opposition forces. At Russia’s insistence, language was dropped that would have excluded from the process “those whose continued presence and participation would undermine the credibility of the transition and jeopardize stability and reconciliation.”

Even so, Clinton insisted, Russian diplomats had convinced her that “they have no continuing strategic interest in Assad remaining in power” and will press Assad to undertake a political transition.

She added that the requirement for mutual consent guaranteed that Assad would have to step down because the opposition would never accept his participation in a transitional government. By the same logic, however, Assad would have little incentive to accept the Geneva plan in the first place.

We have supported the Obama administration’s unwillingness to intervene militarily in Syria or to arm the Syrian opposition. But if the violence continues and a civil war threatens peace between Syria and its neighbors, the pressure for military action by the U.S. and its allies will increase. The Geneva agreement offers an alternative, but only if Clinton’s assessment of Russian intentions is correct.