For the first time since the 1991 Gulf War, a U.S. fighter jet (a carrier based F-18) shot down another jet fighter in the air (a Syrian Su-22) in Syria in defense of its allies in the war against ISIS in Syria that is one part of a complex civil war there.
The U.S. military spends an immense amount of time and money developing fight aircraft optimized for air to air combat and training pilots to conduct it, but, in part because of that developed superiority in capability, almost never actually does.
Also, notably, Iran has joined the fight against ISIS by firing ground based missiles at ISIS targets in Syria. This move not only retaliates against recent ISIS terrorism in Iran (which as a Shi'ite state is anathema to Sunni ISIS in addition to the fact that Iran has backed the rump Iraq government fighting ISIS in Iraq). It also demonstrates the military capability of Iran to strike far outside its borders, which coupled with nuclear weapons which it claims to have stepped back from developing, could pose a real threat to Israel.