Russian climate envoy Anatoly Chubais has resigned from his post at the Kremlin and left the country out of opposition to Russian President Vladimir Putin‘s attack on Ukraine, Bloomberg reports Wednesday, per people familiar with the situation.

According to The New York Times, Russian state news agency Tass has reported that Chubais only stepped down from his role, not left the country. But per The Moscow Times, sources close to him have told the media that the now-former official is in Turkey.

If confirmed, Chubais, 66, would be “the highest-level official to break with the Kremlin over the invasion,” Bloomberg writes. He is “is one of the few 1990s-era economic reformers who’d remained in Putin’s government and had maintained close ties with Western officials.” He actually even gave Putin his first job at the Kremlin, per Bloomberg.

Last week, Arkady Dvorkovich — senior economic adviser to former Russian President Dmitry Medvedev and a deputy prime minister until 2018 — resigned as head of state-backed Skolkovo technology in protest of the invasion. Dvorkovich “is one of only a few former senior officials to speak out against the war,” Bloomberg notes.