The US has rejected Russia's demand to bar Ukraine from Nato, amid warnings Russia might invade its neighbour, BBC reported.
Secretary of State Antony Blinken was giving Russia a formal response to its demands to resolve the Ukraine crisis.
Russia had issued a written list of its concerns about the expansion of the Nato military alliance and related security issues.
Among them was a demand for Nato to rule out the possibility of Ukraine and others ever joining the alliance.
