In his Aug. 12 op-ed column, “The left’s slippery slope,” Richard Cohen attacked the Council for a Livable World and our research organization, the Center for Arms Control and Non-Proliferation, as “isolationist and selfish.”

Our opposition to U.S. military escalation in Iraq is rooted in protecting human life. Our hearts go out to those suffering in Iraq, and we strongly support humanitarian relief for them.

If a U.S. military engagement had been designed as a limited strategy to rescue Yazidis and to evacuate U.S. personnel, we would have reacted differently. But the open-ended nature of the stated mission was and continues to be alarming. The commitment has escalated from sending in a few hundred advisers to limited airstrikes to helping to mount an offensive against the Islamic State.

Haven’t we learned that we cannot drop political solutions from military aircraft? Most military and political leaders agree that Iraq cannot be helped until its government fully includes the Shiite, Sunni and Kurdish people. U.S. bombs and boots on the ground from 2003 to 2011 did not solve Iraq’s political problem. It only fanned the flames of sectarian violence and strengthened the hands of the jihadists.

We join the overwhelming majority in the House and a growing number of senators in calling on the president to seek congressional approval for the use of force in Iraq.

The real slippery slope is another unwinnable war with untold lives to be lost.

Angela Canterbury, Washington

The writer is the executive director of the Council for a Livable World and the Center for Arms Control and Non-Proliferation.