Two Spanish soldiers died when a suicide bomber drove into a convoy in western Afghanistan, while US coalition forces separately killed 14 militants who fired on them, officials said.
The suicide bomber attacked the troops in the western province of Herat, which generally experiences much less violence than southern and eastern provinces.
Carmen Chacon of the Spanish Defense Ministry said six Spanish armored military vehicles were escorting 12 Afghan army trucks on when the suicide bomber rammed his truck into the last vehicle in the convoy. Two Spanish soldiers were killed and four were wounded, she said.
More US and NATO troops have died in Afghanistan this year than in any other year since the 2001 US-led invasion. Militant attacks have become increasingly sophisticated and powerful.
In the east, in Khost province, US coalition forces stopped suspected militants in a vehicle yesterday, and when they approached the vehicle those inside began firing, said Col Greg Julian, a US military spokesman.
Julian said helicopter gunfire was also used against the attackers and 14 were killed.
The province's governor, Arsallah Jamal, said the 14 men were civilian construction workers and were not militants. But Julian insisted that the 14 were militants.
"The main thing is they started firing on these guys (soldiers) after they made the vehicle stop," Julian said.
Civilian deaths caused by US and NATO military forces is a hugely sensitive issue in Afghanistan. This week the US said a joint US-Afghan investigation found that 37 civilians were killed during a battle between US troops and Taliban militants in the village of Wech Baghtu in Kandahar province.