The lock prevents gamers in North American, Europe, and Asia from playing online with one another. Addressing the complaints, Schneider said that the restriction was meant to ensure solid connection performance for those playing online. nope
"[In a multiplayer match] the person with the worst connection brings down the whole group to his/her worst connection level," Schneider told Joystiq. "When playing in Versus mode three people can be highly adversely affected by one player with a bad connection. We use the region lock to minimize the likelihood of this occurring."
Moreover, Schneider explained that a change in the game's physics in the Asian version, which was altered to remove the ability to shoot corpses due to territorial requirements, also had a role in the region lock. The differing physics between the Asian and Western versions of Army of Two would cause a match to de-sync and ultimately fail.
The producer went on to assure gamers that EA is actively pursuing a solution that would allow region-to-region play sometime in the future. "We are looking to find a way where we can do it and not expose users to super slow connections," Schneider said.