Ukraine is marking 23 years of independence amid the ongoing crisis in the east of the country.
President Petro Poroshenko has presided over a military parade in Kyiv's Independence Square -- known locally as the "Maidan" -- where armored vehicles armed with antitank weapons and machine-guns and trucks towing missile systems followed behind columns of soldiers.
Crowds of Ukrainians, many sporting the national colors of blue and yellow, sang the country's anthem as the flag was raised.
Speaking to the crowd of thousands in the square, Poroshenko announced that Ukraine will spend some $3 billion on re-equipping the army in 2015-2017.
The Ukrainian defense ministry says its current budget is $1.5 billion.
Poroshenko said Ukraine would be under constant military threat for the foreseeable future.
The anniversary comes as tensions continue in the country's east, where pro-Russian rebels still hold two major cities, Donetsk and Luhansk.
Ukrainian forces have encircled the two rebel strongholds.
Pro-Russian separatists in Donetsk force-marched dozens of Ukrainian prisoners of war before along the city's main street, in a bid to mock Kyiv's Independence Day celebrations on August 24.
Eyewitnesses said the soldiers were largely unshaven and disheveled, and dressed either in combat fatigues or civilian clothes.
People shouted "Fascists! Fascists" at the group, who walked with heads bowed.
Meanwhile, a shell hit a hospital in central Donetsk in the early hours on August 24, damaging a morgue and two other hospital buildings.
Medical officials said the staff and patients were sent to a basement shelter. No one was hurt.
On August 23 shelling attacks killed six civilians – including a child -- in Donetsk's residential neighborhoods.
Kyiv accuses Moscow of sending in weapons and personnel through parts of the frontier controlled by the rebels. Russia denies the claim.
Russia unilaterally sent hundreds of aid trucks into Ukraine through a rebel-held border point on August 22, saying it had lost patience with Ukraine's delaying tactics, a move that Ukraine promptly described as an invasion.
By mid-afternoon on August 23, all the vehicles had returned to Russia, Paul Picard of the Organization for Security and Cooperation in Europe (OSCE) told reporters in Donetsk.
Russia said the trucks carried only food, water, generators and sleeping bags to Luhansk.
Unrest in eastern Ukraine began in mid-April, one month after Russia annexed Ukraine's Crimean peninsula.
According to the United Nations, more than 2,000 people have been killed, and some 340,000 forced to flee their homes during the conflict.