Defence Secretary Chuck Hagel on Thursday said he is worried about a potential division within NATO as countries in the north want to focus on the growing threat from Russia, while other alliance members in the south are more worried about the influx of foreign fighters from northern Africa.
In his final appearance at a NATO meeting as secretary, Hagel delivered a sobering message to the allies, saying they must be able to address all challenges on all fronts at the same time.
"I am very concerned by the suggestion that this alliance can choose to focus on only one of these areas as our top priority," Hagel said at a news conference in Brussels. "This is a time for unity, shared purpose, and wise, long-term investments across the spectrum of military capability.
Hagel, who resigned under pressure from President Barack Obama's Cabinet, is expected to be replaced as early as next week by Ashton Carter, whose nomination hearing before the Senate Armed Services Committee was on Wednesday.
NATO nations have long been split over where the alliance should focus its resources. And the events of the last year, with Russia threatening one NATO flank and Islamic extremists terrorising the other, has only sharpened that debate.
Russia's annexation of the Crimean peninsula and its military support for separatists along Ukraine's border have unsettled countries in Eastern Europe, including the Baltics and Poland, who worry they may be next.
At Thursday's meeting, in fact, NATO defence ministers were poised to more than double the size of the alliance's Response Force - a move largely aimed at Russian actions in Ukraine, although some argue the capabilities could be used in other crises.
Hagel struck a less strident tone in his final message to NATO than his two predecessors did.
Tired of the US bearing the brunt of the military responsibilities for the alliance, Robert Gates, in 2011, delivered a grim speech warning that NATO faced a "dim if not dismal future" because of European penny-pinching.
Two years later, Leon Panetta used his speeches to push the alliance to be more innovative and find ways to contribute more resources.
Hagel took a more optimistic approach, saying that while the challenges are demanding, he believes NATO will be up to the task.
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