Terrorist groups have used the Middle East as a breeding ground for planning to attack the US and its allies. However, since 9/11 many American lives have been lost and these terrorist groups have been severely weakened. Defense One puts out an opinion article about just how removing troops immediately might be dangerous. Instead, troops should be pulled out slowly and steadily.
Source: https://www.defenseone.com/ideas/2020/11/better-way-fight-forever-war/170161/