As critics questions NATO's relevance now, its members still feel the organization has a place in today's world.
Ambassador Kolinda Grabar, NATO's assistant secretary general, is in Chicago ahead of the summit. She says that the alliance is critical to keeping allies and partners safe, particularly with the economic challenges many nations face.
"The circumstances are changing in the world, but so is NATO changing and we are adapting to the changes in the security environment and adopting to globalization and everything that it brings with it," said Ambassador Grabar.
Grabar personally chose some of the photos at an exhibit that opens Friday at the Pritzker Military Library. She says the images of NATO operations are different than the images that most see.
"Chicago showcases the strengths of the transatlantic link in deeply personal terms," she said.
At the top of the summit agenda is Afghanistan and transitioning security from NATO to Afghan forces.
The mission in Afghanistan was the only instance of NATO invoking Article 5, defending an alliance member as an attack on one is an attack against all.
The NATO was created in 1949 to address a growing Soviet threat. That threat has passed and the future of NATO is still evolving.
Political science professor John Allen Williams hopes to see an alliance with a clearer focus. He moderated a discussion Thursday afternoon about NATO's future with the National Strategy Forum.
"Be conscious of what unites us intellectually as well as strategically and morally. I think that would be very useful. And then that is a basis for what we do going forward,"Allen said.
NATO leadership will make a case for relevance of the alliance at the summit. But undoubtedly the debate over NATO's future and mission with continue long past this weekend.