“War of the Worlds” began taking over the world Wednesday, launching internationally with an impressive $13.4 million at 4,958 theaters in 46 territories. The day-and-date opening established numerous milestones for UIP, which is handling the Tom Cruise/Steven Spielberg tentpole. Initial results also backed up recent optimism that “War” will have enough clout to direct the offshore B.O. back toward last year’s lofty heights. Japan saw the best results, with $2.8 million at 830 playdates, the fourth-best UIP launch in that market and topping Cruise’s “The Last Samurai” and the Spielberg/Cruise movie “Minority Report” by 37%. Italy, which has been beset by disappointing performances from tentpoles, checked in with a solid $1.33 million at 282 sites, a figure that’s UIP’s biggest Italian opening day and the fourth biggest ever in the Italo market. Mexico followed with $1.26 million at 359 engagements, marking the second-best Wednesday launch after “Shrek 2.” Spain, which has been slumping in recent months, saw $1.2 million at 345 locations, repping the best opening for a Cruise film.