Speaking of Afghanistan on Tuesday, Gates said that the Taliban is changing its tactics there — from large-scale firefighters to a "significant increase in terrorist acts," including roadside bombs and suicide attacks, similar to the one that unsuccessfully targeted Afghan President Hamid Karzai on Sunday.
At least one police officer has been arrested in connection with the assassination attempt, deepening concerns about the Taliban's infiltration of Afghan security forces.
Gates said, however, he does not have a sense that the infiltration is any worse that it has been before. He said that it is important to screen the security forces well and that military trainers working with those forces need to make that a focus of their efforts.
On other matters, Gates said it was critically important for Congress to approve funding for an anti-drug trafficking program to aid Mexico.
The so-called Merida Initiative is a $500 million proposal to counter drug crime in Mexico. While the Pentagon portion of the program is small, the US military has worked with Mexico to provide intelligence, surveillance and equipment to counter drug cartels.
"We have a shared concern and a shared threat in the drug cartels," Gates said, adding that it will benefit the US to enhance Mexico's ability to deal with them.
He added that if Congress failed to approve the funding -- which is included in the emergency war funding bill -- it would be "a real slap at Mexico."
This is Gates first trip to Mexico City and only the second visit in recent history by a Pentagon chief. The only other US defense leader to travel to Mexico was William Perry, in 1985.