This month, the Iraq war—in which I served as a U.S. Marine more than a decade ago—turns 18. As a result, soon there will likely be service members deploying to Iraq who were born after the war began in 2003. When they arrive, they will find the conflict remains a dangerous one for Americans, as evidenced by the recent deadly rocket attacks against American bases. Instead of conducting potentially unconstitutional and escalatory airstrikes in Syria to “defend” American troops in Iraq, who are performing a mission that is not necessary for our safety, President Joe Biden should withdraw the...