The Egyptian military says, its air force has killed 19 Islamic extremists in the volatile Sinai Peninsula. It says in a statement today that the strikes in northern and central Sinai on terrorist strongholds of the local Islamic State group affiliate also destroyed four vehicles. <br/><br/>The announcement comes two days after police said they killed one of the militants involved in an attack on a checkpoint that killed a policeman near south Sinai's famed Saint Catherine's Monastery earlier this week.