Colombian police have created the first counter-nuclear arms unit in the region dealing with leftist rebels.
The new Centre for Nuclear Security will try to prevent members of the Revolutionary Armed Forces of Colombia (Farc) from obtaining nuclear material to make a "dirty bomb".
Intelligence officials say computers belonging to the Farc proved they had been trying to obtain nuclear material.
They believe the rebels intend to use the material to cause maximum damage.
Since 2008, when the Colombian army found several computers belonging to the slain Farc commander known as "Raul Reyes", the authorities have been working on a theory that the guerrillas have ambitions involving nuclear arms.
At a news conference in Bogota, the new head of the unit, Gen Rafael Parra, said emails found on the computers proved that since 2005 the Farc had been trying to buy nuclear material in Ukraine.
Venezuelan nuclear ambitions
"It's clearly the intention of the Farc to obtain uranium in Europe. It's obvious that if it tries to do this, then it's for the sole purpose of using it against the people it has been terrorising for years," Gen Parra told reporters.
The inauguration of the centre comes just days after Colombia's neighbour Venezuela signed a contract with Moscow for a new nuclear reactor.
The BBC's Jeremy McDermott in Colombia says the Colombian authorities have long accused President Hugo Chavez of Venezuela of arming the Farc.
However, at the launch of the counter-nuclear arms centre one of its senior officials, Anitta Nilson, insisted there was no link between the new unit and developments in Venezuela.
She said the work of her unit was "in no way political".