The United States and NATO on Wednesday formally responded to Russia's demand for security guarantees in Europe, offering to continue engaging in diplomacy but warning Moscow that it will face "serious consequences" if it opts to stage a new invasion of Ukraine.

Amid the escalating tensions due to the concentration of Russian troops on its border with Ukraine, both Washington and the North Atlantic Treaty Organization sent their separate written responses to the Kremlin within the time period established last week.

The US message was delivered in Moscow by the Washington's ambassador to Russia, John Sullivan, at the Russian Foreign Ministry.

US Secretary of State Antony Blinken said at a press conference that the document specifies the concerns of the US and its allies about Russian actions to undermine security as well as an evaluation of the concerns expressed by Moscow.

Now the ball is in the Russian court, Blinken remarked, adding that Moscow must decide whether or not to choose the path of diplomacy or confrontation.