Biden announced Tuesday that the US will deliver to Ukraine a $625 million military aid package.
Two Russian diplomats said the package risks a direct clash between Russia and the West.
Russia's ambassador to the US said it was "an immediate threat to the strategic interest of our country."
The new US military aid to Ukraine risks a direct clash between Russia and the West, two Russian diplomats warned.
The Biden administration announced a new $625 million military aid package for Ukraine on Tuesday.
Russia's ambassador to the US Anatoly Antonov reacted by saying "We perceive this as an immediate threat to the strategic interest of our country."
"The supply of military products by the US and its allies not only entails protracted bloodshed and new casualties but also increases the danger of a direct military clash between Russia and Western countries," he said on Telegram on Wednesday, according to Reuters.
And Konstantin Vorontsov, the head of Russia's delegation to the UN Disarmament Commission, told the UN General Assembly's First Committee on Tuesday: "The US continues to pump more weapons into Ukraine, facilitating the direct participation of its fighters and advisers in the conflict."
"Not only does this prolong the fighting, but it also brings the situation closer to a dangerous line of a direct military clash between Russia and NATO."
The warnings may be part of Russia's apparent ongoing effort to discourage the West from helping Ukraine.
The US and Western countries have been giving weapons and other aid to Ukraine since Russia invaded on February 24.
Those weapons have become more advanced as the war continued, and as Ukrainian forces successfully pushed Russia back.
But Western help has been limited out of a desire to avoid a direct military conflict with Russia.
That meant many Western nations and NATO did not send their own troops into Ukraine, did not declare a no-fly-zone over Ukraine, and tried to strike a balance with how many - and what kind of - weapons they sent.
Russia's tactics appear to involve trying to discourage the West from helping by issuing warnings.
A NATO official warned in July that Russia had "purposefully raised the level of risk for the possible use of nuclear weapons" to try and "discourage Western Allies from offering military support to Ukraine."
Even as the West tried to strike a balance, some US national security officials said earlier in the conflict that they worried the weapons and other support being given to Ukraine would make a direct conflict with Russia more likely, The New York Times reported in March.
But what's included in the US's aid packages increasing shows how the US has grown more confident in the Ukrainian military as the conflict continues.
The package Biden announced on Tuesday includes four High Mobility Artillery Rocket Systems (HIMARS).
These rocket artillery systems are long-range, high-precision rocket launchers that can strike targets 50 miles away.
"The capabilities we are delivering are carefully calibrated to make the most difference on the battlefield and strengthen Ukraine's hand at the negotiating table when the time is right," Secretary of State Antony Blinken said in a statement Tuesday.
White House Press Secretary Karine Jean-Pierre said Tuesday that the package comes after Russian President Vladimir Putin formally announced the annexation of four regions in Ukraine last week - Kherson, Zaporizhzhia, Donetsk, and Luhansk.
Putin's move has been widely condemned by Ukraine, Russia's neighboring countries, and the West.