U.S. Air Force Secretary Deborah Jones said on Wednesday that she considers Russia to be the biggest threat to American national security, according to Reuters. Tensions have risen recently in light of what Washington views as an increasingly confrontational Kremlin.

"I do consider Russia to be the biggest threat,” James told Reuters after a series of meetings and visits with European allies, including Poland. The U.S. is urging its NATO allies to commit to spend 2 percent of their gross domestic products on the defense, though the countries doing so have been slow to make the commitment. “This is no time to in any way to signal a lack of resolve in the face of these Russian actions.”

Russia has been seen as an increasingly aggressive force in the region since the uprising in Ukraine. Putin has announced the expansion of his country’s intercontinental ballistic missile capacity as well, and there have been a string of close encounters between NATO aircraft and Russian aircraft in what is suspected to be a threat from Putin to western countries. Russia is also reportedly developing multipurpose missile launchers that it will install onto ships in the Russian Navy. The new launchers will be able to shoot different types of missiles from the same launcher tube.

In response, the United States recently threatened to send the top American F-22 fighter jets to the region to keep the Kremlin threat in line.

Just five of NATO’s 28 members have committed to the 2 percent of gross domestic product spending on member defense programs. On Wednesday, the United Kingdom became the fifth to do so, and pledged five years of spending.

James recognized on Wednesday that European economies are experiencing a particularly difficult moment right now with the Greek debt crisis. That situation  threatens to destabilize economies in the region and potentially knock Greece out of the eurozone altogether.