In their Oct. 23 op-ed, “Time for U.S. action in Syria,” John Allen and Charles R. Lister made the same critical mistake the Obama administration has: They offered no realistic plan for what would happen in Syria after the ousting of President Bashar al-Assad. There must be a means to protect all the confessional groups in Syria, including the Alawites. Such a means does not exist in anything the United States and others who want peace propose to do. Without that, Mr. Assad and his people will fight on, and Russia will continue to exploit the opportunities that we created for it, with Moscow profiting all the more so if we escalate militarily without a viable political framework.

The simple “Assad must go” stance also would align the United States with Sunni states’ geopolitical objectives and keeps us enmeshed in the Sunni-Shiite regional civil war. There may still be time for serious U.S.-led diplomacy. But it must begin with so-far-absent strategic analysis that includes keeping us from being a cat’s-paw for others’ ambitions.

Robert E. Hunter, Washington

The writer, a former U.S. ambassador to NATO and former National Security Council official

for the Middle East and Europe, is a senior fellow at the Center for Transatlantic Relations

at the Johns Hopkins School of

Advanced International Studies.

John Allen and Charles R. Lister outlined a series of steps the United States could take to stop the Assad regime’s war crimes and bring Syrian President Bashar al-Assad to the negotiating table. Most of the options they recommend have been considered in Washington policy circles for years: more advanced weapons to vetted opposition units, targeted strikes against Syrian military facilities and stronger sanctions on the regime’s external partners.

Curiously, Mr. Allen and Mr. Lister left out any risks that would be associated with this strategy. They seem to play down the possibility of Moscow escalating the war in response to U.S. military strikes on its Syrian client. While they mentioned possible commingling between Russian and Syrian forces, they ignore the likelihood that Russia would retaliate if some of its personnel were killed in the course of U.S. airstrikes.

Mr. Allen and Mr. Lister also did not make a convincing enough case that sending more powerful weapons to moderate opposition forces would improve the situation, particularly when extremists on the ground seem to outnumber moderates. Can the United States be confident that these weapons won’t simply be taken by extremist factions on the battlefield?

Their argument should be considered as worthwhile suggestions to right a horrible conflict. But we shouldn’t be blind to the costs either.

Daniel R. DePetris, New York

The writer is a fellow at Defense Priorities.

John Allen and Charles R. Lister warned of a “future, inevitable U.S. intervention” if we do not quickly adopt a series of lethal and nonlethal measures. The authors should be reminded that Russia, with its presence in Syria, has created what we established for the defense of Western Europe during the Cold War years: a tripwire that if crossed leads automatically to war, and in the nuclear age with possible terminal consequences. The authors’ measures cannot avoid tripping the Russian wire.

Benjamin Hoge, Alexandria