A US helicopter has crashed in northern Iraq, killing all eight passengers and four crew, the US military has said.
The UH-60 Blackhawk came down just before midnight on Saturday, some 12km (seven miles) east of the town of Talafar, seen as a rebel stronghold.
The US military said the cause of the crash remained under investigation.
Five marines have also been killed over the weekend. Three died in attacks in the western town of Falluja and two were killed by separate roadside bombs.
The Blackhawk helicopter was part of a two-helicopter team moving between bases when communications were lost, a US military statement said.
An immediate search and rescue operation was launched and the aircraft's wreckage was located in a sparsely populated area at about noon on Sunday.
Talafar, about 150km (90 miles) from the Syrian border, is seen as a centre for Iraqi insurgents and is thought to be a staging-post for foreign fighters.
Last September, US and Iraqi forces claimed to have killed 200 insurgents and driven out many more in an assault on the town.
Meanwhile, the US military confirmed it had conducted what it said was an anti-terror operation at the headquarters of the influential Sunni Association of Muslim Scholars.
Witnesses quoted by Reuters news agency said US troops slid down ropes from helicopters as soldiers on the ground burst into the Umm al-Qura mosque complex .
A spokesman for the clerical group condemned the raid as a "crime", saying it had been carried out as punishment for its stance against US-led operations in Iraq.
US military spokesman Barry Johnson said the pre-dawn raid had been prompted by a tip-off regarding "significant terrorist related activity in the building" and was timed to minimise risk to civilians.
On Saturday, one marine was killed by a roadside bomb 80km (50 miles) west of Baghdad and a second while driving near Ferris, about 60km (35 miles) north of Baghdad, the US military said.
Three more marines were killed by small arms fire in Falluja on Sunday while "conducting combat operations against the enemy", a spokesman said.
Ten US marines were killed and 11 wounded by a roadside bomb outside the town in December.
Falluja was the scene of a massive US-led operation against insurgents in November 2004.
Meanwhile, a French engineer kidnapped by an insurgent group in December has been released, Iraqi security officials and the French government confirmed on Sunday.