U.S. Defense Secretary Robert Gates says the demilitarization of Europe is limiting NATO's ability to fight wars, including in Afghanistan.
In Washington Tuesday, Gates said there are too few NATO helicopters and cargo aircraft in Afghanistan. He said the demilitarization of Europe has gone from a "blessing" in the 20th century to an "impediment" to achieving "real security and lasting peace" in the 21st century.
He said real or perceived weakness can tempt potential adversaries to be more agressive.
The Pentagon chief spoke at the National Defense University, where civilian and military officials from NATO member countries gathered to discuss the future of the alliance.
On Monday, U.S. Secretary of State Hillary Clinton called for closer cooperation between Russia and NATO. In her address to the seminar, she called for NATO to broaden its approach to defend against international threats like terrorism and nuclear proliferation.
The North Atlantic Treaty Organization was originally formed after World War Two to guard against Soviet threats, but Clinton said now the organization wants "a cooperative NATO-Russia relationship that produces concrete results."
Other speakers at the seminar include former U.S. Secretary of State Madeleine Albright and NATO Secretary-General Anders Fogh Rasmussen, who expressed regret for civilian deaths in a recent NATO operation in Afghanistan.