Russia's defense ministry says it has launched attacks on Ukrainian military facilities. Ukrainian authorities say Russia has attacked not only the country's east but also the south and outside the capital Kyiv, killing at least eight people.

Officials of the Russian ministry said on Thursday that its forces are using precision weapons to degrade Ukrainian military facilities and airfields.

They later said Russia has gained air supremacy in Ukraine after degrading its air defense.

They said Ukrainian border guards are putting up no resistance.

The General Staff of Ukraine's Armed Forces said Russian attacks began in eastern Ukraine around 5 a.m. on Thursday.

Military facilities in Kramatorsk, a key military hub in the east, reportedly came under attack, along with those in the Kharkiv region in the northeast, Boryspil just outside Kyiv, and the south.

Ukraine's border guard service says Russian attacks also took place in the north, along the country's border with Belarus.

Russia kept troops in Belarus even after the two countries ended joint drills on Sunday.

The border guard says Russian forces are also carrying out attacks from Crimea. Russia unilaterally annexed the southern Ukrainian region in 2014.

Ukraine's internal affairs ministry quotes police as saying Russian attacks have killed eight people in the Odessa region in the south and Mariupol in the Donetsk region in the east. More people were reportedly injured or left missing.

Prior to the military operation, the Russian presidential office said on Wednesday that pro-Russian separatist forces in eastern Ukraine had asked Moscow for military help.

President Vladimir Putin announced in a televised speech on Thursday morning that Russia will carry out a special military operation to support the separatists.

Russia's military operations are taking place despite warnings from Western nations.

The attacks have drawn condemnation from the United States, the European Union and other countries and international organizations.