A shipment of plutonium from scrapped US nuclear warheads has arrived at a French reprocessing plant, despite protests from environmental activists.
It took police two hours to remove the protesters
The 125kg (275lb) of plutonium reached Cherbourg aboard two armed British freighters early on Wednesday.
It was then loaded onto lorries and driven to the plant in nearby La Hague, accompanied by a heavy police escort.
Demonstrators mounted roadblocks on Tuesday ahead of the ships' arrival, but were dragged away by police.
Activists say the transport of such material is vulnerable to attack.
The companies involved reject this and say the protesters' actions are just "media-seeking gestures".
The plutonium has been in transit since the two British-registered ships left North Carolina last month.
It is to be treated at La Hague, 18km (12 miles) from Cherbourg, before being driven nearly 1,000km (660 miles) to south-east France for further reprocessing at two facilities run by the Areva-Cogema company.
In Tuesday's protest, Greenpeace members chained themselves to a truck to try to block the road from the port of Cherbourg to La Hague.
Police and firefighters took two hours to cut loose about a dozen protesters who were attached under and inside the vehicle. Greenpeace says four of its activists were detained.
The environmental organisation argues that the long distances of road transport pose a big risk.
"A rocket-propelled grenade could go through those trucks so easily and expose plutonium around this area," Greenpeace activist Thomas Breuer said.
But Cogema spokeswoman Laurence Pernot said the aim was to make the plutonium safe.
"We don't understand how an organisation that has always been against nuclear weapons proliferation could wage a protest against an operation aimed at curtailing that same proliferation," she said.
The plutonium shipment is part of an agreement between the US and Russia to destroy plutonium from excess nuclear warheads.
Cogema will process the material and convert it into mixed oxide nuclear fuel (MOX), which will then be shipped back to the US for civilian use.
The US Department of Energy says the plutonium has to be shipped overseas because there is not a plant capable of carrying out the conversion process in the US.
In a separate incident, a truck carrying 4.5 tonnes of enriched uranium was hit from behind by another truck near the French city of Orleans, AFP news agency reported.
"The load of radioactive material was not damaged," the regional authorities said.