The charges cite two articles of Ukraine's Criminal Code: Part 2 of Article 111 (high treason committed under martial law) and Parts 2 and 3 of Article 436-2 (justifying, recognizing as lawful, or denying Russia's armed aggression against Ukraine, and glorifying its participants).

Investigators allege Mendel conducts "information-subversive activity against Ukraine." The SBU says she used her prominence and experience in state communications to spread "information narratives beneficial to the aggressor state, aimed at discrediting Ukraine and weakening its international support."

The suspicion is based on her public statements in media and on social media. In an interview with American conservative commentator and former Fox News host Tucker Carlson in May, she said: "I believe that Ukraine is on the verge of disappearing" and "You see, my nation is degrading." According to the investigation, she also claimed that there is "no freedom of speech" in Ukraine and that the "country is full of prohibitions."

The Prosecutor General's Office separately notes that on her Facebook page Mendel spread messages about benefits the Ukrainian authorities receive from continuing the war, propaganda, and the persecution of dissidents. According to the investigation, such materials were intended to shape an international audience's perception of Ukraine as a state that does not deserve further support, and of its leadership as an obstacle to achieving peace. Inside the country, investigators believe, they were aimed at increasing disappointment and demoralizing society.

The SBU said Mendel is outside Ukraine, and therefore "comprehensive measures to hold her accountable" are continuing.

Yulia Mendel served as press secretary to the president of Ukraine from June 3, 2019, to July 9, 2021. Before that, she was a journalist on various Ukrainian television channels and worked with major foreign publications.