Secretary of Homeland Security Michael Chertoff on Monday blamed tightened security on the U.S.-Mexico border for increased violence there, and he said the border probably will not be fully secured until 2011, three years after President Bush leaves office. "(Increased violence) is what typically happens when you start to enforce and make it harder to fight over the shrinking pie, so to speak, and who gets the best opportunity to exploit the additional space that's left," Chertoff said at a news conference at the U.S. Customs and Border Protection headquarters in Washington, D.C. on Monday. "That's a good sign," he...