Defense Secretary Robert M. Gates, center, U.S. Ambassador to Mexico Antonio Garza, left, and Army Lt. Gen. Peter Chiarelli, right, attend a meeting with Secretary of Government Juan Mourino and Secretary of Foreign Affairs Patricia Espinosa, both not pictured, in Mexico City, Mexico, April 29, 2008. Defense Dept. photo by Cherie Cullen

Jacinta Camara gives Defense Secretary Robert M. Gates and his wife, Becky, a tour of the National Museum of Anthropology as U.S. Ambassador to Mexico Antonio Garza listens, Mexico City, Mexico, April 29, 2008. This was the first visit by a U.S. Defense Secretary in 12 years. Defense Dept. photo by Cherie Cullen

Defense Secretary Robert M. Gates meets with U.S. Marines assigned to the U.S. Embassy in Mexico City, Mexico, April 29, 2008. Defense Dept. photo by Cherie Cullen

Defense Secretary Robert M. Gates conducts a media roundtable after meeting with officials and touring the National Museum of Anthropology, Mexico City, Mexico, April 29, 2008. Defense Dept. photo by Cherie Cullen

Defense Secretary Robert M. Gates, left, walks with Director of Protocol Lt. Col. Ruben Montesinos as his wife, Becky Gates, walks with Ambassador to Mexico Antonio Garza, upon their arrival in Mexico City, Mexico, April 29, 2008. Defense Dept. photo by Cherie Cullen

U.S. Army Staff Sgt. Robert Groves nails a sign in place as an Iraqi boy holds it, April 27, 2008. The sign instructs visitors to the newly opened Civil Military Operations Center on Joint Security Station Sadr City. Groves is assigned to the 4th Infantry Division's 3rd Brigade Combat Team. U.S. Army photo by Sgt. Zachary Mott

Tech. Sgt. Lem Torres hoists up a survivor on a litter during a search and rescue mission about 230 miles south of New Orleans, April 25, 2008. Responding to a request for support from the U.S. Coast Guard, two HH-60G Pave Hawk helicopters of the 41st Rescue Squadron and a 71st Rescue Squadron HC-130P King performed a 10-hour mission to retrieve a boatload of stranded immigrants in distress that had been picked up by a passing ship. Sergeant Torres is a 38th RQS pararescueman. U.S. Air Force photo by Senior Airman Gina Chiaverotti

U.S. Navy sailors from the amphibious assault ship USS Essex push an AV-8B Harrier, assigned to the VMA-513 "Nightmares," onto the ship's aircraft elevator while at sea, April 29, 2008. U.S. Navy photo by Petty Officer 3rd Class Gabriel S. Weber