A security breach exposed secret US documents, at least one of which was labeled "top secret", detailing US and NATO plans for Ukraine's spring offensive against Russia, the New York Times reported on Thursday.

Pentagon stated that it has begun an assessment of the reported security breach. Deputy Press Secretary Sabrina Singh claimed, "We are aware of the reports of social media posts, and the Department is reviewing the matter."

Initially, the documents, which contained detailed information regarding the weaponry, battalion strengths, and other sensitive data, spread quickly through Twitter and Telegram via pro-Russian channels, according to The Times.

Classified documents leaked caused a reaction from the Pentagon. The #US admin is trying to persuade Twitter & Instagram to delete these documents relating to the #US plans in #Ukraine, deployment of forces, casualties of belligerents, supply of weapons & more v @Spriter99880 pic.twitter.com/JD6UMfNLrc

— Elijah J. Magnier 🇪🇺 (@ejmalrai) April 7, 2023

It is worth noting, however, that the information being circulated is not very recent, and is at the very least five weeks old. The most recent one available was dated March 1st according to the report.

The documents included summaries of training schedules pertaining to 12 Ukrainian combat brigades, nine of which were being trained by the US and NATO. The brigades required 250 tanks, and more than 350 mechanized vehicles, the report noted.

The files also indicate expenditure rates for armaments under Ukraine's military control, including the HIMARS rocket systems.

According to US media outlets, military experts cautioned that, allegedly, certain records have been changed as part of a Russian misinformation operation, with one document raising the number of Ukrainian army casualties while lowering Russian battlefield losses.

US invests new $2.6 billion in proxy war in Ukraine

The Pentagon revealed on Tuesday that the US will be sending a new package worth $2.6 billion of military aid to Ukraine to fuel their forces in their war against Russia. 

"The United States will continue... to provide Ukraine with capabilities to meet its immediate battlefield needs and longer-term security assistance requirements," the Pentagon said in a statement. 

The military aid package is reported to include ammunition for HIMARS (High Mobility Artillery Rocket Sytems), artillery rounds, light weaponry, Patriot tank munitions, NASAMS (National Advanced Surface-to-Air Missile Systems) defense systems, and Bradley Infantry Fighting Vehicles ammunition.

The bulk of the military assistance package ($2.1 billion) is sourced from Ukraine Security Assistance Initiative (USAI) funds: which purchase weapons directly from the industries, while the remaining half billion dollars are sourced from US stocks. 

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