Russian President Vladimir Putin denounced Kosovo's creation of an army as destabilizing for the Balkans during a visit to Belgrade that underscored his ally Serbia's conflicted approach to joining the European Union.

President Aleksandar Vucic's Serbian Progressive Party, which is itself facing anti-government protests, mobilized thousands of its members in the capital Thursday to show support for the Russian leader. Vucic is looking to leverage Moscow's backing in striking a deal to normalize ties with Kosovo, one of the biggest hurdles to both countries' EU membership aspirations.

Vucic said he didn't believe that an agreement with Kosovo was close, and Russia would have to sign off on any deal, sending a signal that he doesn't accept EU opposition to a proposal for the neighbors to redraw their borders. European leaders fear new demarcations could incite similar demands across the region and trigger the kind of ethnic strife that killed more than 100,000 people during the violent breakup of Yugoslavia.