Ukraine’s military has shot down two of Russia’s command planes, in one of the most disastrous days for the Kremlin’s air power since the start of Vladimir Putin’s full-scale invasion. Valerii Zaluzhnyi, Ukraine’s commander in chief, said his air force had destroyed an A-50 long-range radar detection aircraft and an Il-22 control centre plane. Both were flying above the Sea of Azov on Sunday when they were hit at 9.10pm local time. The A-50, which detects air defences and coordinates targets for Russian jets, crashed instantly, killing its crew. The badly damaged Il-22 appears to have made an emergency landing at an airfield in Anapa, Russia. It is unclear how Ukraine managed to target and shoot down the planes. One theory is that a Patriot anti-aircraft missile battery – supplied by the US – was used. This, however, would involve moving the system close to the frontline where it could be detected. Russian officials said they have “no information” about what exactly happened. Pro-Kremlin bloggers suggested the planes were hit by friendly fire or even shot down by a team of British SAS operatives using surface-to-air missiles. Whatever the cause, the incident is a blow for Russia’s aviation, and a morale boost for Ukraine’s armed forces. Kyiv’s counter-offensive last year failed and in recent months Russia has launched a wave of attacks across the east, along a frozen frontline, seeking to regain the initiative. According to the UK’s Ministry of Defence, the Kremlin has only six working A-50s in service. Each plane costs $330m to build. Last February partisans in Belarus attacked another A-50 while it sat on an airbase near Minsk. It is unclear how much damage they caused. Since last year Ukraine has systematically degraded Russian military infrastructure in occupied Crimea, targeting radar stations and other installations. It bombed the headquarters of Russia’s Black Sea fleet in the port of Sevastopol and has forced naval vessels to relocate to safer harbours. Kyiv now appears to be challenging Russia’s domination of the Sea of Azov, which includes the ports of Berdyansk and Mariupol, seized in 2022. In a statement on Monday, Zaluzhnyi said two Russian planes were destroyed in what he called “an excellently planned and conducted operation” in the south of the country. Ukraine’s air force spokesperson, Yurii Ihnat, said that the Il-22 had been damaged beyond repair. He added that the A-50 spy plane was “the priority target for us”. An unconfirmed image on social media showed the Il-22’s tail section, apparently pitted with shrapnel damage. Russia has suffered a series of embarrassing setbacks to its ageing Soviet-era air fleet in recent weeks. Last week, Ukraine’s intelligence agencies said they were behind an attack on an Su-24 jet, parked at an airbase outside the Russian city of Chelyabinsk. It was burned down. A teenager was later arrested. In December Russia’s own air defences shot down a Russian Su-25 jet. Earlier the same month Ukraine destroyed an Su-24M bomber. Ukrainian commentators reacted with glee to the news, which dominated social media channels on Monday. Illia Ponomarenko, the former defence correspondent for the Kyiv Independent newspaper, wrote simply: “Confirmed by the Ukrainian command. The biggest air kill of the war so far.” Ukraine’s air force playfully hinted that there was more to come. It posted a graphic of the two downed planes, with the words: “Who did this?”