The United States needs to increase the number of military exercises and training programs across Europe and strengthen NATO's intelligence sharing to better counter Russian aggression in the region, Defense Secretary Ash Carter said Friday after a lengthy, closed-door meeting in Germany with top American defense and diplomatic leaders.

He acknowledged that the current international economic sanctions against Russia haven't stopped Moscow's military support for rebel separatists in Ukraine.

Carter also said the U.S. and others are worried President Vladimir Putin would use similar tactics elsewhere in the region and is positioning Russia as a U.S. adversary.

"There are other things we need to be doing in recognition of the fact that, at the moment at least, Vladimir Putin does not seem to be reversing course," Carter told reporters traveling with him shortly after leaving the meeting. "Therefore we need to adapt, in a long-term sense, to that reality."

Other U.S. leaders insist the sanctions have worked because they've battered Russia's economy. But Carter made the distinction that they haven't fostered change.

"It's a sign of how heedless the Russian government seems to be about the long-term welfare of its own people that it has not yet resulted in a change, in a reversal at least of course, which is what we want out of Russia," he said.

Carter's meeting with his military commanders from around the globe, as well as 14 U.S. ambassadors from the region, came on the eve of the Group of Seven weekend summit in the Bavarian Alps, a meeting to which Putin was disinvited. Western leaders at the G-7 are expected to further condemn Russia for its suspected role in the escalating violence in Ukraine, but stricter punishments are not expected.

Western leaders say Moscow is supplying rebels with manpower, training and weapons. Russia rejects those claims.

Still, military and diplomatic leaders in the meeting expressed concern about the tactics they said Russia has used in Ukraine — what Carter described as a mixture of subversion, sophisticated threat making and manipulation of information.

"All this cocktail that you saw in Ukraine — is that something we're worried about them using elsewhere? Absolutely. Was that discussed? Absolutely. It is concerning to the NATO countries for sure," Carter said.

In Ukraine, a fragile cease-fire worked out in February has been repeatedly broken, and a major battle erupted in eastern Ukraine earlier this week. Both sides blamed the other for the latest spike in violence.

Carter's meeting at the headquarters of U.S. European Command involved nearly 40 people, including the heads of the Pentagon's Africa, Pacific, Middle East, special operations and cyber commands, as well as U.S. ambassadors from across Europe and Eastern Europe. Its aim was to assess how effective the economic sanctions and U.S.-backed military operations have been in deterring Russia and discuss what more the U.S. and allies can do.

The more-than-four-hour session came at the end of Carter's 11-day, around-the-world trip, which focused largely on challenges in the Asia-Pacific region.

U.S. officials said no decisions were made during the meeting, but Carter said the group discussed a number of actions the U.S. can take. As an example, he said increased U.S. military exercises and training in the region, including in the Baltics, have been successful.

He also repeated his call for allies and partners to do more — from increasing their defense spending to participating more in the military exercises and training,

And, he said, it's "really time to make some progress" on NATO's long discussed desire to improve its intelligence and information sharing, both in terms of Russia and the escalating threat from Islamic State militants and the growing risk they pose beyond the territories they've taken in Iraq and Syria.