Russia has formulated several options as an excuse to invade Ukraine, including the potential use of a propaganda video showing a staged attack, the United States said on Thursday, as the Kremlin condemned American troop deployments in the region.

Russia, which seized Crimea from Ukraine in 2014 and backs separatists in the east of the country, is demanding security guarantees including a promise Nato will never admit Kyiv as it has amassed some 100,000 troops near the...