WASHINGTON, June 14 (Reuters) - The new $325 million U.S. military aid package for Ukraine pushes Washington deeper into the "abyss" of the conflict, Russia's ambassador to the United States, Anatoly Antonov, said early on Wednesday.

The package, which includes munitions for air defence systems, ammunition and vehicles, comes as Ukraine is shaping its long-expected counter-offensive. In the past week, Ukrainian forces lost some tanks and armoured vehicles provided by western allies while making small initial territorial gains.

"The United States is getting deeper and deeper into the abyss of the Ukrainian crisis," Antonov was quoted as saying in a post on the embassy's Telegram messaging channel.

"Apparently, the strategists from the United States somehow do not understand that no amount of weapons, whatever involvement of mercenaries, will be able to turn the tide in the course of (Russia's) special military operation."

Russia refers to its actions in Ukraine as a "special military operation", rather than a war. Kyiv and its allies are calling it an unprovoked act of aggression to grab land.

The United States, the European Union and other allies of Ukraine have sent billions of dollars worth of military assistance to Kyiv since the start of Russia's invasion in February 2022.

Ukraine President Volodymyr Zelenskiy welcomed on Tuesday the new U.S. aid, saying on Twitter that it was what Ukraine's defence forces needed, an "effective assistance in liberating the territories temporarily occupied by the Russian aggressor."