Russia has warned it would quickly take “retaliatory measures” if the U.S. and its allies reject its security demands and continue their “aggressive” policies.

The statements Wednesday ratcheted up pressure on the West amid concerns that Moscow is planning to invade Ukraine.

Russia has repeatedly denied it has any such designs.

But the United States and its NATO allies are worried because Russia has massed an estimated 100,000 troops near Ukraine’s border.

At the heart of the standoff are questions about Ukraine’s future; Russia has demanded guarantees that NATO will never admit the country and that the alliance will roll back troop deployments in other former Soviet bloc countries.

Some of these are nonstarters for NATO, creating a stalemate that many fear can only end in a war.