Three US drone strikes have killed on Monday at least 18 people on the volatile Afghan-Pakistan border, officials say, according to the BBC. The first two attacks hit a seminary and a compound in the South Waziristan tribal area, officials said. The third hit a vehicle. They come days after al-Qaeda operative Ilyas Kashmiri was reported to have been killed in a US strike in the area. Militants have vowed to avenge his reported killing, as well as the death of Osama Bin Laden last month. Ilyas Kashmiri headed a group that specialises in co-ordinated multiple strikes on targets, and was a key commander in al-Qaeda. He is widely believed to have masterminded an audacious attack on the Mehran naval airbase in Karachi last month, in which six well-organised militants managed to hold off Pakistan’s equivalent of the US Navy Seals for 15 hours.