WASHINGTON —

       The Biden administration on Wednesday was set to provide Russia a written response that rejects most of its demands over Ukraine, as the Kremlin signaled that such a rebuff is certain to escalate the crisis.

       With global tensions raging over a possible Russian invasion of the pro-West former Soviet republic, the Biden administration’s expected actions and Moscow’s reaction appeared to dampen hopes that diplomats could find a peaceful resolution to the standoff.

       “If the West continues its aggressive course, Moscow will take the necessary retaliatory measures,” Russian Foreign Minister Sergei Lavrov told reporters ahead of an expected announcement by U.S. Secretary of State Antony J. Blinken confirming that the U.S. response has been transmitted to President Vladimir Putin‘s government.

       Russia’s main demand, that Ukraine be permanently barred from joining NATO, has already been turned down by the U.S. and the leadership of NATO.

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       While most experts agree that Ukraine membership in the transatlantic alliance is not coming any time soon, the State Department says that such a position will not be conveyed publicly to Russia.

       “An open door is an open door,” the department’s spokesman, Ned Price, said, referring to the alliance’s position that any nation has the sovereign right to apply to join.

       Tens of thousands of Russian troops are massed on Ukraine’s eastern and northern borders. If they move deeper into the country — as Russia did in 2014 — it would be the largest such invasion since World War II, President Biden said on Tuesday. He has said he will not send U.S. troops to Ukraine but has put 8,500 service members on high alert for rapid deployment to NATO countries that border Ukraine. The U.S. is also surging military aid to the besieged country.