Ukraine claimed its air forces shot down three Russian war planes in one of its most successful military operations since the beginning of the conflict 22 months ago.

The three Russian Su-34 fighter aircraft, which are armed with guided bombs and missiles, were shot down Friday in Ukraine’s war-torn Kherson region in the country’s south, according to reports.

Ukrainian Air Force spokesperson Yuri Ihnat praised the maneuver on national television as a “brilliantly planned operation.”

“There haven’t been Su-34s for some time in our positive statistics,” he said, citing the model as one of Russia’s most modern aircraft for bombing and other assaults.

Moscow did not comment on the claims, but Russian military bloggers reported the losses, according to reports. Fighterbomber, one of the most influential bloggers, reported the loss of an unspecified number of planes, saying they had probably been downed by US-made Patriot missiles.

During his daily television address, Ukrainian president Volodymyr Zelensky said that the downing of the planes would force Russian pilots attacking Ukrainian targets to consider that “none of them would go unpunished,” the BBC reported.

Earlier, Zelensky cited a report by HUR, the country’s military intelligence agency, that reported a slowdown in Russia’s military capacity because its supply lines have been disrupted, a development echoed Saturday by the U.K. Defense Ministry.

Separately, Russia warned of “serious consequences” if Europe and the U.S. carry out efforts to give seized Russian assets to Ukraine, a plan under discussion among Western countries. More than $300 billion of Russian Central Bank reserves was frozen in the West after Moscow’s invasion in February 2022, all of which could handed over to Ukraine, which is desperate for funds as the U.S. and European countries begin to balk at continued support for the fighting.

Moscow threatened to sever diplomatic relations with the U.S. should it confiscate the Russian assets frozen under sanctions. Deputy Foreign Minister Sergey Ryabkov said, the US “must not act under an illusion that Russia is clinging with both hands to diplomatic relations with that country.”

At a press briefing, Kremlin spokesman Dmitry Peskov threatened retaliation against any countries that hand Russian funds over to Ukraine. “Russia will never leave those who do it alone,” he said, according to reports.