Russia has halted flights to Egypt as more signs point to the possibility that last weekend’s airline explosion was caused by a bomb. And as Slate’s Daniel Byman explains, if this really was the work of ISIS, it’s a whole new (and much scarier) ballgame.

+ “Egypt still has a very large conventionally oriented, war-with-Israel military, which is odd, given the kaleidoscope of problems they have around them.” In an interview with Jeffrey Goldberg, Defense Secretary Ashton Carter explains that the states in the region need to get in the fight against ISIS.