Acknowledging a Mexican drug war that is "sowing chaos in our communities," President Barack Obama signaled Thursday he will not seek the reinstatement of a U.S. assault weapons ban but instead step up enforcement of existing laws against taking such weapons across the border.

Despite a campaign promise to see the lapsed ban renewed, Obama was bowing to the reality that to do so would be unpopular in politically key U.S. states and among Republicans as well as some conservative Democrats.