MOSCOW (AP) — The Russian president on Tuesday reiterated his demand for guarantees from the U.S. and its allies that NATO will not expand eastwards, blaming the West for “tensions that are building up in Europe.”

Vladimir Putin's speech at a meeting with Russia's top military brass came just days after Moscow submitted draft security documents demanding that NATO deny membership to Ukraine and other former Soviet countries and roll back the alliance’s military deployments in Central and Eastern Europe — bold ultimatums that are almost certain to be rejected.

The demands — contained in a proposed Russia-U.S. security treaty and a security agreement between Moscow and NATO — were drafted amid soaring tensions over a Russian troop buildup near Ukraine that has stoked fears of a possible invasion. Russia has denied it has plans to attack its neighbor but pressed for legal guarantees that would rule out NATO expansion and weapons deployment there.

Putin charged Tuesday that if U.S. and NATO missile systems appear in Ukraine, it will take missiles only minutes to reach Moscow.

“For us it is the most serious challenge — a challenge to our security,” he said, adding that this is why the Kremlin needs “long-term, legally binding guarantees” from the West, as opposed to “verbal assurances, words and promises” that Moscow can't trust.

Putin noted that NATO expanded eastward in the later 1980s and early 1990s, depite what he said were assurances that Russia's worries were groundless.

“What is happening now, tensions that are building up in Europe, is their (U.S. and NATO's) fault every step of the way,” the Russian leader said. “Russia has been forced to respond at every step. The situation kept worsening and worsening, deteriorating and deteriorating. And here we are today, in a situation when we're forced to resolve it somehow."

Russia’s relations with the U.S. sank to post-Cold War lows after it annexed Crimea in 2014 and backed a separatist insurgency in Ukraine’s east. Tensions reignited in recent weeks after Moscow massed tens of thousands of troops near Ukraine’s border.

Putin has pressed the West for guarantees that NATO will not expand to Ukraine or deploy its forces there and raised the issue during a video call with U.S. President Joe Biden two weeks ago.

The Russian president said Tuesday that Moscow hopes for a “clear, comprehensive response” to its demands from Washington, and there are “certain signals” that the U.S. is prepared to give it.

“We hope for constructive, meaningful talks with a visible end result — and within a certain time frame — that would ensure equal security for all. This is what we will strive for,” Putin said.