MIRANSHAH (AFP) A US drone strike killed four militants Monday and destroyed a rebel compound in North Waziristan, local security officials said. Officials say unmanned US aircraft have significantly stepped up attacks on Taliban and Al-Qaeda-linked operatives in the semi-autonomous region this month, clocking up at least 19 attacks in 24 days. Mondays strike took place in Khushali Toorikhel village southeast of Miranshah, the main town in North Waziristan, the tribal district that has been the focus of the covert drone campaign as a Taliban and Al-Qaeda stronghold. We can now confirm that four militants were killed when a US drone fired two missiles on a militant compound, a senior security official told AFP on condition of anonymity. Another security official confirmed the attack and the death toll. We dont yet know the identities of those killed, the official said. Security officials also said US drones carried out missile strikes in North Waziristan on Saturday and Sunday, killing at least 11 militants.