From an article in the "Guardian" in March about the drone that crashed in Zagreb, quote:
A drone that
flew undetected over several Nato countries from Ukraine crashed overnight in the Croatian capital, Zagreb, triggering a loud blast but causing no injuries, Croatian authorities have said.
The Croatian president, Zoran Milanović, said it was clear the drone came from Ukraine.
The large drone flew for at least 560km apparently undetected by air defences in Croatia, Hungary and Romania, all members of the western military alliance.
The Croatian president, Zoran Milanović, said “the serious incident” must be thoroughly investigated to determine
“how a relatively unsophisticated drone flew for over an hour over Nato countries without being detected”.
He said that the drone crashed in Zagreb after running out of fuel.
Military experts of the War Zone online magazine said the aircraft was likely to have been a Soviet-era Tu-141 Strizh drone that must have severely malfunctioned. It said Ukraine was the only known operator of the Tu-141.
The Ukrainian defence ministry adviser, Markian Lubkivskiy, was quoted by the Interfax news agency as denying the drone was Ukrainian. He put the blame for the incident on Russia.
“This drone did not have Ukrainian markings,” he was quoted as saying. “There were red stars on it” – a symbol of the Russian military.
The Russian embassy in Zagreb said the drone was made in Ukraine and that Russian forces had stopped using Tu-141s since the breakup of the Soviet Union in 1991.