The United States said on Wednesday it had set out a diplomatic path to address sweeping Russian demands in eastern Europe, as Moscow held security talks with Western countries and intensified its military build-up near Ukraine with new drills.

In a written response to Russia's demands delivered in person by its ambassador in Moscow, the US repeated its commitment to upholding Nato's "open-door" policy while offering a "principled and pragmatic evaluation" of the Kremlin's concerns, Secretary of State Antony Blinken said.