For an alliance that only a few months ago was still struggling with defining its mission after a decade of war in Afghanistan, Ukraine is a God-sent gift. No longer can there by any doubt over NATO's central raison d'être: providing for the territorial defense of Europe against an increasingly aggressive and revisionist Russia. Putin's actions in Ukraine not only threaten countries on Europe's eastern flank, they also risk unraveling the entire post-Cold War Eurasian security order.

It is therefore encouraging that the alliance is treating the Ukraine crisis seriously. NATO has already taken several steps to reassure worried allies in Central and Eastern Europe. It has increased air patrols in the Baltic Sea and naval patrols in the Eastern Mediterranean. The U.S. has also sent 600 troops to be based in Poland and the Baltic states on a semi-permanent basis. Unless the situation improves, further such efforts are to be expected in coming months leading up to the NATO summit in Wales in September.

But while NATO's refocus on Europe is welcome, the alliance should be wary of pivoting back to Europe too hard. Though the alliance must do more to boost security in Central Europe, simply going "back to basics" – as some allies seem to favor – is not a viable option for the world's premier security organization. Unlike during the Cold War when NATO's purpose was primarily to defend against a possible Soviet invasion, today several reasons compound why NATO must have broader global focus.

While the U.S. is still fully committed to its alliance obligations (as the recent efforts to boost in American troops in Central Europe confirms), it will increasingly expect Europeans to provide for more of its security. Doing so would allow the U.S. to continue focusing on pivoting to Asia – something that ultimately benefits Europeans as well. The foundation for a new transatlantic bargain is accordingly that Europe takes more responsibility for security threats in its neighborhood in return for continued U.S. commitment to Article 5.

For the United States, NATO is only valuable as long as it makes a vital global security contribution. Certainly, keeping Europe peaceful and Russia at bay is a significant in and by itself, but NATO also has play a critical role elsewhere. This includes the Middle East and North Africa, the Gulf, and possibly even the Asia-Pacific. While there is clearly no appetite to extend alliance membership to non-European countries, promoting stronger partnerships between NATO and countries such as Australia, Japan and the Gulf Cooperation Council (GCC) make a lot of sense, especially given today's tough budget climate.

Cooperation with key partners must move beyond political dialogue to practical initiatives that focus on strengthening partners' capability to conduct joint missions with NATO in the future. Here, NATO has great potential to serve as a strategic hub to promote military interoperability and develop critical competences such as intelligence, surveillance, and reconnaissance and strategic airlift. NATO should also expand the scope and scale of its joint exercises and increase partners' involvement in the planning and command of joint operations and improving information-sharing during such missions.

Certainly, Russia is the foremost security challenge to Europe right now, and it requires a strong NATO response to reassure worried Central European allies as well as efforts to deter Putin from further aggressions. But NATO cannot just be about Russia. It should also play a vital role in other parts of the world. As NATO prepare for the summit in Wales in September, Russia should therefore not be the only topic of conversation. NATO leaders must also think about how to advance the alliance's partnerships with other key countries around the world. This will allow the alliance to re-focus on territorial defense while still maintaining a global reach.

Brattberg is a resident fellow at the Brent Scowcroft Center for International Security at the Atlantic Council in Washington, D.C.