Russia’s muscle-flexing is due in part simply to the fact that the country is spending more on its military and has re-established abilities eroded during the post-Soviet chaos of the 1990s. When Mr. Putin first became president in 2000, Russia spent $9.2 billion on its military, but this has since risen 10 times and will increase again this year despite a slumping economy, hammered by a collapse in the price of oil and also by Western sanctions.

“The signal they are sending is that the situation in the 1990s was an exception,” General Lunde said.

Jens Stoltenberg, a former Norwegian prime minister who became NATO’s secretary general late last year, said that Russia’s new assertiveness was not just a result of increased funding and revived ability. He said it was also “part of a broader picture where we see that Russia is willing to use force,” most notably in Georgia in 2008 and, more recently, in Ukraine.

“It is this total picture that gives us reason for concern,” Mr. Stoltenberg said.

Ukraine, he added, is very different from Norway, which is a member of NATO. Ukraine is outside the alliance and has no prospect of joining any time soon. However, Mr. Stoltenberg said, Norway and other NATO countries that share a border with Russia also have to deal with Russian efforts to “intimidate its neighbors,” no matter what their status.

Russian air activity along the borders of NATO, the northern parts of which are patrolled by fighters based in Bodo, increased 50 percent from 2013 to last year, according to the alliance. At the same time, Russia sharply increased so-called snap military exercises, training maneuvers that, in violation of established procedure, were either announced at the last minute or kept secret.