A look at the main issues for the NATO alliance at the summit meeting Sunday and Monday.
The players • An alliance formed in 1949 to deter Soviet aggression. The central principle is that an attack in Europe or North America against any member is an attack against all. The alliance has grown to 28 member nations, ranging from the United States, Britain, France and Germany to former Soviet bloc countries such as the Czech Republic, Hungary and Poland. Albania and Croatia are the newest members.
Afghanistan • The summit will affirm the shift in NATO's military mission in Afghanistan from a combat role to an advisory role next year, and on plans to help underwrite the Afghan military after the NATO-led military mission ends two years from now. NATO is pledging to maintain a multinational combat force in Afghanistan until sometime in 2014, with a firm deadline to end the mission by 2015.
NATO modernization • Most alliance members have endured economic reversals that make any major new defense spending unappealing or impossible. The alliance is laboring under the weight of outdated or incompatible equipment and suffers major gaps in military capability that the better-equipped and better-funded U.S. military often has to fill. Some of those shortfalls were on display during last year's successful NATO air mission in Libya.
Missile defense • The alliance will declare that it has partly completed a missile defense shield for Europe. The system has achieved "interim capability," against possible missile threats from Iran or elsewhere, NATO claims. Russia opposes the system and has rebuffed NATO efforts to form a partnership. Russian President Vladimir Putin is not attending the summit, largely because of the missile defense split.