In his Aug. 12 Outlook piece, “How. When. Whether. Stopping Syria’s war,” Kenneth M. Pollack overstated the case that there are only two ways to end a civil war, such as Syria’s: Help one side win or deploy “an outside force to suppress the warring groups and then build a stable political process.”

At least seven “ethnic” civil wars, such as Syria’s, were settled by negotiated agreement in the first six decades after World War II — including in South Africa, Mozambique and, most recently, in Liberia in 2003. In some of the cases, peacekeepers did provide a reassuring presence after the combatants reached a power-sharing agreement, but in none did an occupying force impose the peace, as Mr. Pollack suggested would be necessary in Syria.

If we assume that the only options are aiding the rebels or deploying an occupying force, that is self-fulfilling. But there has always been a third option in Syria: The international community could join together and tell both sides that it will not permit either to win (unless one engages in mass slaughter of civilians), thereby forcing them to negotiate a power-sharing peace agreement. That option might not be wholly satisfying to any party, but it might save lives and promote regional stability far better than Mr Pollack’s two options.

Alan J. Kuperman, Austin