Second Iran-Iraq War
Military action
Taking advantage of the United States dissolution, Iran invades Iraq in a war motivated by religion, imperialism and a need to satiate internal dissent. As a result, the entire region descends into war.
Iran was plagued by a growing internal dissent for years. With America gone, its leadership decided that it is time to pacify its dissenters by foreign conquests. Surprisingly, it worked, at least for the time being. With weak Iraqi government receiving another blow due to United States collapse, the war was quickly over. However, invasion on Iraq has caused a major instability in the region.
Saudi Arabia decided to seize Yemen openly - and did so quickly. Soon it also changed Kuwait and UAE into de facto satellite states. And in 2029 Turkey invaded Syria, slowly pushing both Kurds and the Syrian government south.