Russian pranksters pretending to be Ukrainian Prime Minister Volodymyr Groysman fooled Energy Secretary Rick Perry into taking a hoax phone call.

As reported by The Washington Post, the pranksters Vladimir “Vovan” Kuznetsov and Alexei “Lexus” Stolyarov told Perry’s office they were interested in a follow-up call after the secretary held a real meeting with Groysman in June. On the call, Perry walked them through energy policy issues, such as coal shipments and the US’s withdrawal from the Paris climate accords.

But there were signs that something was amiss. Toward the end of the 22-minute call, the prankster impersonating Groysman explains that Ukrainian President Petro Poroshenko personally, in his off-time, created a biofuel using manure and home-brewed alcohol, and adds that it is already being sent to eastern Ukraine to aid in disputes with Russia.

The conversation has been released online, although only Perry’s side is available in English.

The pranksters have earned a reputation for similar stunts. Perhaps most prominently, in 2015 they impersonated Vladimir Putin in a call to Elton John.