Gov. Rick Perry says he's open to the idea of sending U.S. troops into Mexico to fight the drug war. The Texas governor told MSNBC this morning that border violence has escalated dramatically since George W. Bush was governor a decade ago. He said more aggressive federal tactics are needed. "You have a situation on the border where American citizens are being killed, and you didn't see that back when George Bush was the governor," he said. Host Chuck Todd asked whether Perry would advocate military involvement on the Mexican side of the border. Perry responded: "I think we have...