BELGRADE, Serbia (AP) — Russia on Thursday blasted Serbia for exporting arms to Ukraine, saying it’s a stab in the back by its longtime Slavic Balkan ally.

“Serbian defense enterprises, contrary to the ‘neutrality’ declared by official Belgrade, continue to supply ammunition to Kyiv,” said the Russian Foreign Intelligence Service, SVR, in a statement.

The Serbian export of arms to Ukraine, mostly the Soviet-era-caliber ammunition still used by Ukraine’s defense forces, has long been known and reported, but it’s not clear why the Russian foreign security service decided to react now.

There was no immediate reaction from the Serbian officials.

Serbia’s arms deliveries to Ukraine have been an open secret since early 2023, when the first leaks of the exports were published. Moscow then vowed to look into the matter.

Although claiming he wants to take Serbia to the European Union, Serbian populist President Aleksandar Vucic has maintained close relations with Russia. He defied EU warnings and attended Russia’s Victory Day parade in Moscow .

Vucic’s appearance in Moscow for the May 9 parade was widely condemned in Brussels, with EU officials warning that such actions seriously jeopardize Serbia’s EU path. The officials said that it was inappropriate for Vucic to stand side by side with Russian President Vladimir Putin, considering Moscow’s invasion of Ukraine.

Vucic has said his decision to attend Putin’s military parade, which marked the World War II victory over Nazi Germany, was part of efforts to maintain “traditional friendships” — Russia is a fellow Slavic and Orthodox Christian nation — while seeking EU entry.

Serbia, which relies almost fully on Russia for energy, has refused to join Western sanctions on Russia over the full-scale invasion of Ukraine and hasn’t supported most EU statements condemning the aggression.

Russia has until now remained silent about widespread reports that Serbia is supplying Ukrainian forces with ammunition and the Russian statement on Thursday came as a surprise.

“A simple scheme using fake end-user certificates and intermediary countries serves as a cover for anti-Russian actions,” the Russian SVR statement said.

“The contribution of Serbian defense industry workers to the war unleashed by the West, the outcome of which Europe would like to see as a ‘strategic defeat’ of Russia, amounts to hundreds of thousands of shells … as well as a million rounds of ammunition for small arms,” the statement said.

“It is unlikely that such supplies can be justified by ‘humanitarian considerations.’ They have one obvious purpose — to kill and maim Russian military personnel and the civilian population of Russia.”

“It seems that the desire of Serbian defense industry workers and their patrons to profit from the blood of fraternal Slavic peoples has made them completely forget who their real friends are and who their enemies are,” the Russian statement said.