Missiles fired from an unmanned US aircraft killed six militants in a Pakistani tribal region near the Afghan border, officials said.
The missiles struck two vehicles in Anghar Kala village near Miran Shah in North Waziristan - the second such attack since massive floods hit Pakistan.
They spoke on condition of anonymity because they were not authorised to release the information to the media.
The tribal region is a haven for various Islamist militant groups. The main organisation operating there is the Haqqani network, which focuses on attacking US and NATO troops across border in Afghanistan.
Pakistan's leadership has raised concerns that the insurgents might exploit instability and chaos caused by the massive flooding, the country's worst-ever natural disaster.
The US has tried to improve its public image in Pakistan by sending significant flood aid, though Saturday's airstrike shows it is not willing to abandon the widely unpopular drone attacks.
The US rarely discusses the CIA-run missile campaign, but officials have said in the past it has proven a valuable tool in the battle against al-Qaida and Taliban fighters sheltering in Pakistan's tribal areas.
Separately, a bomb exploded at a checkpoint manned by pro-government tribesmen and police in north-western Pakistan on Saturday, killing six people.
The attack happened in Mohmand, a tribal region 45 miles (75 kilometres) north-west of the main city of Peshawar. The dead included a policeman, a passer-by and four members of a peace committee set up to check militant movements.