Past NATO enlargement helped create a Europe whole, free, and at peace, but future enlargement, should it occur, faces a hostile and militarily revitalized Russia. This report examines the military requirements and resulting budget costs of extending NATO’s Article 5 commitment to countries such as Ukraine, Georgia, or Bosnia-Herzegovina, which are actively seeking NATO membership, and Sweden and Finland, about which there has been analysis and speculation about membership. Costs to the United States range from $11 billion per year to defend Ukraine to half a billion dollars or less to defend Sweden. The project recommends that NATO incorporate force requirements and cost considerations into its future decisionmaking.
Mark Cancian (Colonel, USMCR, ret.) is a senior adviser with the CSIS International Security Program. Adam Saxton is a former research associate with the CSIS International Security Program, where he supported research related to U.S. force structure, great power conflict, and the international order.
Executive Summary VI
1 | Why This Project? 1
2 | NATO Membership: Cold War Stability Followed by Post–Cold War Enlargement 12
3 | Russian Military Capabilities Today 23
4 | The Current State of NATO Forces and Military Budgets 27
5 | Defending Recently Joined Members: Learning from History 35
6 | Defending Potential Future Members: Forces and Budget Costs 39
7 | Georgia 45
8 | Ukraine 64
9 | Bosnia and Herzegovina 78
10 | Sweden 85
11 | Finland 95
12 | NATO Enlargement and Potential Actions 104
About the Authors 107