By Yusri Mohamed and Ahmed Hassan ISMAILIA, Egypt/CAIRO (Reuters) - Islamic State insurgents attacked several military checkpoints in Egypt's North Sinai on Wednesday in a co-ordinated assault in which at least 70 combatants and civilians were killed -- one of the biggest militant attacks in Egypt's modern history. The action marked a significant escalation in violence in the Sinai Peninsula, located between Israel, the Gaza Strip and the Suez Canal. Islamic State's Egyptian affiliate, Sinai Province, claimed responsibility for the attacks.