On 30 November 2021, Russian President Vladimir Putin stated that an expansion of NATO's presence in Ukraine, especially the deployment of any long-range missiles capable of striking Russian cities or missile defense systems similar to those in Romania and Poland, would be a "red line" issue for Russia.[32][33][34] Putin asked U.S. President Joe Biden for legal guarantees that NATO wouldn't expand eastward or put "weapons systems that threaten us in close vicinity to Russian territory."[35] According to Putin, "If some kind of strike systems appear on the territory of Ukraine, the flight time to Moscow will be seven to 10 minutes, and five minutes in the case of a hypersonic weapon being deployed."[36]