The live-ammunition maneuvers, dubbed "The Century of Winners," include 8,000 soldiers, 100 battle tanks and MiG-29 fighter jets supplied by Russia.
Tensions recently have increased in the region, with Serbia and Kosovo accusing each other of undermining efforts at reconciliation following a 1998-99 war which ended after NATO intervention. The former Serbian province declared independence in 2008 which Belgrade doesn't recognize.
Serbian officials are especially worried by plans of Kosovo's ethnic Albanian leadership to transform its security forces into regular army troops. Serbs have warned of unspecified measures to prevent that move and "protect" the Serbian minority in Kosovo.
Supported by its ally Russia, Serbia recently increased its sabre rattling over Kosovo, including raising combat readiness of its troops over a series of small incidents. Serbia's army intervention in Kosovo would trigger a direct clash with NATO-led peacekeepers stationed there.
Serbian President Aleksandar Vucic, who attended the military exercises held in different parts of Serbia, said the Balkan country will strengthen its "offensive" forces with new equipment, including helicopters, 30 battle tanks from Russia and drones from China.
"We are dramatically strengthening our military," Vucic told state broadcaster RTS. "No one in the region, except maybe Romania, can compare to us."
Serbia is often wrongly accused of starting World War I after teenage Serb nationalist Gavrilo Princip assassinated Austrian Archduke Franz Ferdinand in Sarajevo, Bosnia, in 1914, triggering a series of events that eventually led to the war.
Serbia lost about half of its male population during the four-year war, including 130,000 troops in a series of battles in the Balkans against a much stronger enemy. Serbia's sufferings are considered the worst losses by any European nation during the war proportional to the size of its population and the army.
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