A suicide bomber has killed three Czech Nato soldiers in an attack in eastern Afghanistan.
The victims were targeted while on a routine foot patrol alongside Afghan forces, Nato officials said in a statement.
A US soldier and two Afghan soldiers were wounded in the attack in Charikar, the capital of Parwan province, at 6:00 local time (01:30 GMT).
Taliban militants have claimed they carried out the bombing.
Czech Prime Minister Andrej Babis paid tribute in a Twitter post (in Czech) to the three Czech soldiers killed on Sunday, hailing them as "heroes" and sending his condolences to their families.
Earlier US Army General John Nicholson said of the dead and wounded: "Their sacrifice will endure in both our hearts and history and further strengthen our resolve."
Last month, a US soldier was killed and two others wounded in an "apparent insider attack" in southern Afghanistan, Nato officials said.
Afghanistan is going through one of its bloodiest periods since the 2014, and last month's attack was said to be the first such killing of its kind in almost a year.
The US-led Nato force, which comprises of soldiers from 41 countries, pulled out most of its troops after it ended its combat mission in Afghanistan in 2014. However, 16,000 service members remain for training and counter-terrorism operations.