Warning the situation in Europe is growing “more serious and more complicated,” the U.S. European Command commander says more prepositioned tanks and artillery are needed to support a potential U.S. Army surge.

Europe faces threats from a “resurgent, aggressive Russia,” and from the cancerous expansion of Islamic State militant groups “taking advantage of paths of least resistance,” said Air Force Gen. Philip Breedlove, who has been European Command commander and the Supreme Allied Commander, Europe, since 2013. Testifying Thursday before the House Armed Services Committee, Breedlove said the 2017 defense budget pending before Congress includes a four-fold increase in funding for the European Reassurance Initiative that includes money for more prepositioned equipment in place in Central Europe.

The Army already has deployed an additional set of equipment sufficient for an armored brigade combat team to Europe, and company- and battalion-sized elements out of that set are now being distributed along NATO’s eastern border, Breedlove said. This equipment will be used by the Army’s regionally aligned forces to support training and exercising with allies in Europe. “Storing and maintaining equipment in this manner helps reduce transportation time and costs, and reassures allies and partners in the region of our steadfast commitment,” Breedlove said.

Breedlove said his command fully supports the Army’s effort to further increase its prepositioned stocks in Europe in fiscal year 2017 as part of the European initiative to help “shorten the response time in a time of crisis.”

Breedlove’s testimony came one day after Army Chief of Staff Gen. Mark A. Milley told Congress that his NATO counterparts are “very much in favor of additional U.S. support over there in order to deter Russia” from further aggression. In the last 10 to 15 years, many European countries cut defense spending and reduced capabilities, but some of those countries “are turning that around,” Milley said.

Breedlove’s comments reinforce one of the major findings of a recent report by the Center for Strategic and International Studies, “Evaluating U.S. Army Force Posture in Europe.” That report, commissioned by U.S. Army Europe, recommends that the Army deploy a second rotational armored brigade combat team to the continent and preposition enough equipment there to support eight brigade combat teams, not just the current three.

Breedlove made clear that his preference would be to increase permanently stationed forward forces in Europe. Army end strength in the theater has fallen from more than 300,000 at the height of the Cold War to about 30,000 today.

“Permanently stationed forward forces buy you a lot of things,” he said. “One of those things is relationships, and relationships equal access. I can’t overstate the importance of having that access. You cannot surge trust, you cannot surge relationships. I’m on record multiple times as saying we don’t have enough permanently stationed forward forces in Europe.”

The focus on bulking up prepositioned equipment stocks in Europe is a direct outgrowth of the rapidly shifting nature of the relationship between NATO and Russia, Breedlove said.

“For 20 years, we’ve been trying to make a partner out of Russia, changing our force structure in Europe to reflect a mission of engagement and building partnerships,” he said. “Today, we definitely do not have a partner in Russia. Our resolve now is to be able to meet the challenge of a resurgent, revanchist Russia.”

“We need to be a warfighting force rather than partnership builders,” Breedlove said. “We have to rethink whether we have the capacity and capability to be a warfighting force. We do not. We have to begin reshaping” the European Command and NATO force structure “to deal with a Russia that does not share our norms and values in Europe.”

Breedlove said the “Russia problem presents a new long-term challenge” for the European Command area of responsibility “and our nation. Russia poses an existential threat to the United States, and to the NATO alliance as a whole.”