Heads of state and government of 28 member countries of the North Atlantic Treaty Organization (Nato) on Sunday kicked off their 25th summit in Chicago.
In his opening remarks at the summit, US President Barack Obama said the alliance has been the "bedrock" of member countries' common security and freedom.
Obama noted Natohas adopted a new strategy in its last summit in Lisbon in 2010, saying "in Lisbon, we committed, in Chicago we are delivering".
The alliance's future commitment to Afghanistan and security top the agenda, Xinhua reported.
Obama said the allies will invest in new capabilities and pool resources to face new security challenges, as well as charting next phase of transition in Afghanistan.
The allies will also meet with neighbours and partners to enhance Nato's network of global security partnership.
NatoSecretary General Anders Fogh Rasmussen, for his part, said the summit will renew commitment of the "vital bond" between North America and Europe in the 21st century.
Rasmussen said the allies will discuss transfer of security responsibility to Afghanistan by the end of 2014, as well as support for the country beyond 2014.
He said allies will also make sure Nato is capable of confronting new challenges with a renewed culture of cooperation.
The two-day summit will first address the alliance's security capabilities in an era of austerity, and will devote Monday to the transition in Afghanistan.
Among the summit's likely achievement is a commitment to a milestone in 2013 that Nato forces in Afghanistan will take on support role as Afghan forces take over the lead in combat missions.
The alliance will also announce the purchase of a fleet of surveillance drones, sharing weapons and training facilities, and sustaining nuclear deterrence in Europe, according to US officials.
Components of the European missile-defence system will also be transferred from US to Nato command.