"NATO states are taking over the Black Sea and Ukrainian territory,” Anatoly Antonov said on a YouTube channel on Saturday, Press TV reported.
“There are assumptions, which are voiced here, that certain daredevils or a group of combatants may turn up in Ukraine, who will try to test the strength of Russian defenses, expecting that we will not respond fearing the NATO potential. I would like to say and emphasize unequivocally that it is a very dangerous delusion," he said.
The Russian diplomat stressed that Washington is increasingly expanding the range of weapons delivered to Ukraine with a claim that they are to be used for defensive purposes.
"Militarily speaking, this range of weapons funneled to Ukraine [from the United States] is expanding more and more. The Stinger [man-portable air-defense systems], Javelin [anti-tank weapons] and even our Mi-17 [helicopters] got there," he said.
"They keep saying that these are defensive weapons. But we know what 'defensive weapons' mean, what the US Mk-41 systems are like, which, on the one hand, are certainly defensive, as they are anti-missile systems, but it has already been proven, and the Americans are not concealing now that they can be used for launching intermediate-range and shorter-range missiles," the diplomat underlined.
Russian President Vladimir Putin has warned that the West is escalating the situation in Ukraine by providing Kiev with “lethal modern weapons” and holding drills in the Black Sea region.
The Russian leader said Moscow has been "constantly” raising concerns about the US naval exercises in the strategic region, but the West is taking Russia's warnings lightly.
President Putin and other top Russian officials have repeatedly warned that the expansion of NATO activities near Russia’s borders is a "red line" for Moscow.
NATO has expressed determination to reinforce the security of member states close to Russia following what it claims to be Moscow's “annexation” of Crimea and its backing for pro-Russia separatists in eastern Ukraine.
Antonov also said the “hysteria” surrounding the perceived Russian threat to Ukraine, which is being stirred up in the United States, is aimed at justifying the failures of Ukrainian President Vladimir Zelensky.
"In my opinion, this current hysteria sparked by an alleged Russian threat is a desire to whitewash the failures of the current Ukrainian president," the Russian ambassador to Washington said.
Antonov reiterated that Russia did not intend to attack any country and said the Russian diplomats in the US are open for dialogue on Ukraine.
Earlier in the month, Ukraine claimed there were nearly 100,000 Russian soldiers deployed near its border, and the United States issued warnings over a possible attack by Russia.
Moscow categorically rejected the possibility of an attack, saying Washington is involved in aggressive moves in the Black Sea, where Ukraine and the United States recently held military drills.