Russia has warned the United States to stop supplying Ukraine with advanced weaponry or face "unpredictable consequences," American officials said Friday, according to The New York Times.

The message, first reviewed by The Washington Post but not disclosed publicly, indicated that Moscow is growing more concerned that the U.S. supplied weapons are hindering Russia's tactical strategies, reports the Times.

"We call on the United States and its allies to stop the irresponsible militarization of Ukraine, which implies unpredictable consequences for regional and international security," the message purportedly read.

On Friday, Russian Foreign Ministry spokeswoman Maria Zakharova said Moscow had sent a similar letter to "all countries."

So far, the State Department has refused to comment on the letter's contents, which was titled, "On Russia’s concerns in the context of massive supplies of weapons and military equipment to the Kiev regime."

On Wednesday, President Joe Biden approved $800 million in military aid for Ukraine, which includes helicopters and "contain many of the highly effective weapons systems we have already provided and new capabilities tailored to the wider assault we expect Russia to launch in eastern [Ukraine's Donbas region]. These new capabilities include artillery systems, artillery rounds, and armored personnel carriers."

Back in February before Russia's invasion, the Biden administration was concerned that sending weapons into a conflict zone could provoke Russia. But after capitulating to the pressures of Ukrainian President Volodymyr Zelenskyy and a bipartisan faction of Congress, the administration decided to provide the heavy armament it says Ukraine would need in the next phase of the war.

Andrew Weiss, a former National Security Council director for Russian, Ukrainian and Eurasian affairs, in February before the invasion began recalled that Russian President Vladimir Putin warned that Western nations would face "consequences greater than any you have faced in history" if they became involved in the conflict.

During the beginning stage of the war, Weiss indicated that Putin and Russia possessed a powerful nuclear arsenal. He said Putin's speech was "a very explicit warning about not sending weapons into a conflict zone."

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