NATO is reassessing its fundamental relationship with Russia and focusing on new threats not imagined at its inception in the wake of World War II, a key U.S. diplomat told Stanford students and faculty.

Douglas Lute, America’s ambassador to the North Atlantic Treaty Organization, said Washington and Moscow found a way to collaborate since the collapse of the Soviet Union. But that has changed under President Vladimir Putin, he said.

“It’s clear today that we don’t have the partnership with Russia that we had for two decades,” Lute said. “NATO does not wish to be an enemy of Russia, but Russia has to understand that it will defend its 27 allies.”

He warned Russia that the tactics being used in Crimea “don’t play on NATO territory; these allies will be defended as the treaty demands.”

Lute’s talk on Tuesday capped his two-day visit at Stanford. He spent the day before lecturing in the International Policy Studies course “America’s War in Afghanistan: Multiple Actors and Divergent Strategies” taught by Karl Eikenberry. Eikenberry, a former ambassador to Afghanistan, is now a consulting professor at the Freeman Spogli Institute for International Studies and an affiliate of several of the institute’s centers.

Ambassador Lute spoke to the class about the White House and National Security Council perspective on the war in Afghanistan, drawing on his experience in both the Bush and Obama administrations. 

That will call for a Special Forces-type base in Europe that can defend the 28 nations of the North Atlantic Treaty Alliance from hybrid assaults, he said.

“A cyber attack on a NATO ally could rise to the level of requiring a mutual defense response,” he said.

Lute’s talk was sponsored by the Freeman Spogli Institute for International Studies, The Europe Center, the Center for International Security and Cooperation, and the Center for Russian, East European and Eurasian Studies.