Vice President Mike Pence told leaders of eight Balkan nations on Wednesday that “the future of the western Balkans is in the West,” a signal of the United States’ commitment to southeastern Europe and a warning against Russian encroachment in the region.

Speaking in Montenegro, which defied Russia by becoming the newest member of NATO in June, Mr. Pence praised the tiny nation for its independence.

“Your courage, particularly in the face of Russian pressure, inspires the world and I commend you for that,” Mr. Pence said at a dinner on Tuesday evening.

Russian officials were so incensed by Montenegro’s decision to join NATO that they plotted a coup attempt in October to try to block the country from joining the alliance, Mr. Pence said — an accusation that Russia denies.