The North Atlantic Treaty Organization was formed in 1949 to counter the threat of a Russian expansion in Europe.
It's original 12 member countries included the United States, the United Kingdom, France and Canada.
The military alliance is now 31 countries strong, and Sweden and Finland are expected to apply in coming months.
When Putin invaded Ukraine in late February, NATO began supplying it with weapons, ammunition and other equipment to defend against Russian aggression, despite Ukraine's non-NATO member status.
How much power does NATO have and how are its decisions made?
Why are some countries allowed to be members while others are not?
What more can and will the alliance do to help Ukraine?
Guests:
- Daniel Hamilton, Ph.D., professor and senior fellow in the Foreign Policy Institute at the Johns Hopkins University School of Advanced International Studies, senior nonresident fellow at the Brookings Institution's Center on the United States and Europe, president of the Transatlantic Leadership Network, and former U.S. deputy assistant secretary of state for European security affairs
- Hans Binnendijk, Ph.D., distinguished fellow with the Atlantic Council's Scowcroft Center for Strategy and Security, adjunct political scientist at the RAND Corporation and former senior director for defense policy at the National Security Council
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*This interview was recorded on Tuesday, April 12.