A US drone strike in Pakistan's troubled tribal region killed at least four suspected militants Thursday, dpa quoted an intelligence official as saying. Two missiles struck a compound in Khushali Tori Khel village near Mir Ali, the second-biggest town in the North Waziristan tribal district, according to the official who spoke on condition of anonymity. The identities of the dead were not immediately known, but the mountainous region bordering Afghanistan is a known hub of rebels linked with al-Qaeda and the Afghan Taliban. Like the other six Pakistani tribal districts, North Waziristan is also largely off-limits for journalists and observers, making it hard to get independent confirmation of details about the counterinsurgency campaign. US drone attacks against Taliban and al-Qaeda targets had seen a substantial decrease towards the end of last year, but have risen in recent weeks. Long War Journal, a group reporting on and analyzing the US-led campaign, said six strikes were carried out in first eight days of this year.