WASHINGTON  Defense Secretary Robert M. Gates, who has long called European contributions to NATO inadequate, said Tuesday that public and political opposition to the military had grown so great in Europe that it was directly affecting operations in Afghanistan and impeding the alliance’s broader security goals.

“The demilitarization of Europe  where large swaths of the general public and political class are averse to military force and the risks that go with it  has gone from a blessing in the 20th century to an impediment to achieving real security and lasting peace in the 21st,” he told NATO officers and officials in a speech at the National Defense University, the Defense Department-financed graduate school for military officers and diplomats.

A perception of European weakness, he warned, could provide a “temptation to miscalculation and aggression” by hostile powers.

The meeting was a prelude to the alliance’s review this year of its basic mission plan for the first time since 1999. “Right now,” Mr. Gates said, “the alliance faces very serious, long-term, systemic problems.”