President Barack Obama will use the Military Academy at West Point as his backdrop when he addresses the nation on Afghanistan on Tuesday night.Obama will stand before a crowd of cadets and military personnel when he goes before the cameras to lay out his Afghanistan war strategy; he is expected to call for roughly 34,000 more troops and place a heavy emphasis on an exit strategy. The speech is set for 8 p.m.An “imperative— in Obama’s strategy is ramping up training for Afghan security forces to be able to maintain control after U.S. forces leave, White House Press Secretary Robert Gibbs said Wednesday. Noting that it will cost another $1 million per troop per year, Gibbs acknowledged that the cost of maintaining a presence in Afghanistan will be “very, very, very expensive.— But in his address, Obama will “walk through his decision-making process and give people a sense of the importance of our efforts, but reiterate for them that this is not … an open-ended engagement. Our time there will be limited, and I think that’s important for people to understand,— Gibbs said.