Ex-paramilitary leader Salvatore Mancuso is among those extradited
Colombia has extradited 14 former paramilitary leaders to the US to face charges of drug trafficking.
Officials said the men had failed to abide by a peace deal under which their groups were demobilised.
Under the 2003 pact, the militia leaders were to confess wrongdoing and surrender the proceeds of their crimes.
Colombia's right-wing paramilitaries have been accused of many thousands of killings as well as drug-trafficking and money-laundering.
The latest extraditions come a week after a top paramilitary figure, Carlos Mario Jimenez, was sent to the United States.
"Fourteen leaders of one of the world's largest and most powerful drug-trafficking organizations arrived in handcuffs on US soil today," said Drug Enforcement Administration (DEA) official Michele Leonhart.
They are facing charges of drug trafficking, conspiracy and money laundering and are to be tried in Washington, Miami, Tampa, New York and Houston.
The move took Colombia by surprise and even the men's lawyers only found out when listening to the morning news, says the BBC's Jeremy McDermott in Medellin.
Among those extradited were Salvatore Mancuso, one of the top commanders of the United Self-Defence Forces of Colombia (AUC), Rodrigo Tovar Pupo alias Jorge 40, and Diego Fernando Murillo known as Don Berna.
"Most of the top bosses are there," Colombian Interior Minister Carlos Holguin told local radio.
Top paramilitary figure Jimenez was extradited to the US last week
"In some cases they were still committing crimes and reorganising criminal structures."
The US also argues that many former paramilitary leaders continue to direct drug trafficking networks.
Some Colombians fear, however, that extraditing the militia leaders to the US means they will not face justice in Colombia or reveal their alleged links to many government figures.
Investigations have so far linked dozens of current and former politicians to the paramilitaries - 31 have been jailed.
US officials have said they will co-operate with Colombian prosecutors in their investigations.
President Alvaro Uribe said any international assets the US seizes from the paramilitary leaders would go to compensating their victims in Colombia.
In a national address he said the men had been extradited because they had not co-operated with prosecutors and had denied compensation to their victims by hiding assets.
"This is notice that the law must be respected and terrorism defeated," Mr Uribe said.
The Colombian government last year accused Jimenez, also known as Macaco, of running a criminal empire from prison.
They said he had therefore violated a 2003 peace deal, which obliged paramilitary leaders to surrender and demobilise 31,000 men in exchange for reduced jail terms and extradition protection.
He is to face charges of drug-trafficking and money-laundering in the US.
The paramilitaries were set up and funded by wealthy landowners and drug traffickers to combat left-wing guerrillas.
They have been accused of committing some of the country's worst atrocities and of being responsible for the deaths of thousands of people.