John Ratcliff’s visit to Moscow was not about warning Russia not to invade the Balkans. I suspect that Russia is planning to occupy Svalbard.
Svalbard is a Norwegian-owned group of islands in Arctic. It is a military-free zone per the 1920s Spitzbergen treaty, so there are no defenses at all. But Russia sees it as a strategically important stepping stone to Greenland, Iceland, the UK and northern Canada. It could become a fortress protecting the corridor from the Atlantic to the Arctic and northern Russia. 
Russia already has several hundred citizens on Svalbard supporting a mining operation. Note that Russia also ran a simulated Arctic invasion on their own Franz Josef Land east of Svalbard in 2025. They are building several large bases in other parts of the Arctic. We have virtually nothing anywhere nearby except a radar facility on the other side of Greenland.
Europe and the UK do not even have real navies. If Russia took over Svalbard in a bloodless invasion would NATO vote to fight a war that far from the mainland against the Russian Northern Fleet supported by Russia’s most important bastion of naval, submarine, and nuclear forces at Murmansk/Severomorsk?
