Around two-thirds of those arrested are foreign nationals and nearly half have ties to drug trafficking groups, mainly in Mexico, ICE director John Morton told reporters.

"The purpose of this effort was to target violent street gangs associated with drug cartels, particularly in Mexico," Morton said.

The arrests come just two weeks after an Immigration and Customs Enforcement officer, Jaime Zapata, was killed by members of the Los Zetas drug cartel in Mexico, as the Washington Times reports:

Mr. Zapata and his partner, Victor Avila, were driving from Monterrey to Mexico City, where they were assigned to ICE’s attache office.

Zapata was shot five times in the chest. Mr. Avila was shot twice in the leg, but survived. Neither of the agents was armed, as the Mexican government does not let U.S. law enforcement personnel carry weapons in that country.

The ICE office describes project Southern Tempest as "the largest ever ICE-led gang enforcement operation targeting gangs with ties to drug trafficking organizations."

On top of that, on Monday Mexican police arrested the leader of a drug gang called "The Resistance," the AP reports. But on the same day, police found five dead bodies hanging from a pedestrian bridge in Sinaloa, and in Ciudad Juarez assailants opened fire on a car, killing two men, a woman and a 10-year-old boy.

In Ciudad Juarez alone, the number of civilian deaths in 2010 far outnumbered the total number of civilian deaths in Afghanistan for the same year. Mexican paper La Reforma reported that last year that the number of cartel-related murders surpassed 10,000 in 2010, and the violence has claimed more than 30,000 lives total so far.

For a thorough primer on Mexican cartel violence, see the BBC's Q&A on the topic.