MEXICO CITY — The U.S. ambassador to Mexico said the United States is considering issuing a heightened travel alert in the coming days. "While there is little doubt in my mind that the travel alert should be reissued, it may also be necessary to heighten the alert to better reflect the increasing insecurity in the state of Chihuahua," U.S. Ambassador Tony Garza said. An alert issued last year by the State Department warns Americans about travel in areas of Mexico where foreigners have been targeted. The alert is due to expire April 15. Mexico has suffered a wave of organized crime and drug-related violence that killed more than 2,500 people last year.