Ukrainian President Petro Poroshenko has vowed to increase military spending by $3 billion over the next few years because of the ongoing pro-Russian separatist threat in the east of Ukraine.
Poroshenko made the comment Sunday in Kyiv during a speech marking Independence Day, 23 years after the breakup of the Soviet Union.
He told a crowd of thousands gathered in Independence Square to view a military parade that it is clear the separatist threat will "hang over Ukraine" for the foreseeable future, and the country must be prepared to defend itself.
On Saturday, Western monitors said the Russian aid convoy that crossed into Ukraine Friday had gone back to Russia, easing international tensions as German Chancellor Angela Merkel arrived in Ukraine's capital voicing renewed hopes for peace.
Merkel met with President Poroshenko, and pledged $660 million in German aid to help rebuild cities in eastern Ukraine battered by months of fighting.
Pro-Russian rebels in the Russian-speaking east launched their rebellion in April. Since then, an estimated 2,000 people have been killed as government forces seek to regain control of the region.
Merkel said her visit, just three days ahead of a meeting between the presidents of Russia and Ukraine, comes at "a difficult but decisive time" for Ukraine's territorial integrity. She also warned that Moscow could face further economic sanctions if its support for the rebellion continues.
As the high-level diplomacy unfolded in Kyiv, at least six civilians were reported killed by artillery fire in the key rebel stronghold city of Donetsk, as Ukraine's forces press their fight against rebels near the Russian border.
In a related development, the U.S. State Department voiced shock Saturday over reports that a top Lithuanian diplomat was abducted and murdered by rebels in the the eastern Ukrainian city of Luhansk. Spokeswoman Marie Harf also extended condolences to the diplomat's family and said U.S. authorities were still "seeking information on the circumstances of this tragedy."
Lithuanian authorities reported Friday that Honorary Consul Mykola Zelenec was kidnapped and killed, but did not immediately provide details.
The entry of Russia's convoy into Ukraine, following days of waiting as delivery details were negotiated with Kyiv, raised an outcry from Ukraine, the United States, NATO and the European Union.
White House officials called the crossing a flagrant violation of Ukraine's sovereignty and demanded Russia remove the convoy or face consequences.
In acknowledging the incursion, the Russian Foreign Ministry referred to "endless delays hampering the initial deliveries" and said those delays had become "intolerable." It also described the aid as "urgently needed by women, children and the elderly."
Ukraine and its allies had for days expressed fears Russia could use the aid trucks to smuggle arms to pro-Russian separatists inside Ukraine, or use the convoy as a prelude to a full-scale military operation.
There were no reports by late Saturday of either Russian smuggling linked to the convoy or ongoing Russian military operations in Ukraine territory.
Some information for this report was provided by AP, AFP and Reuters.