The US Department of Defense is trying to determine the source of the leak of classified documents detailing the strategy of the United States and NATO to support Ukraine in the face of the Russian invasion, published last week on social media, according to the New York Times.

In response to a question, the US Department of Defense said it was investigating the matter. "We are aware of press information regarding messages posted on social media and the department is looking into the matter," a Pentagon spokeswoman said.

These documents, dating back to early March, include, according to the American newspaper, the frequency with which Ukrainian forces use ammunition for HIMARS missile launchers and the timetable for the delivery of weapons and training provided by the West to the Ukrainian army.

The newspaper quoted experts as saying that the documents appear correct, but some amendments were made to reflect a better picture of the Russian situation, especially by minimizing the size of Russian losses.

According to these leaks, Kiev is about to form 12 new brigades, including nine trained and equipped by the United States, according to the New York Times.