Ukraine's parliament on Thursday formally recognised the war in the east of the country as a "temporary Russian occupation" in a vote that has infuriated the insurgents and Moscow.
The new law defining the conflict pitting Ukrainian forces against pro-Moscow insurgents came after nearly four years of fighting that has claimed more than 10,000 lives. It broke out after street protests in Kiev toppled a Kremlin-backed leadership.
It has turned into a low-intensity conflict in which no territory changes hands while the sides trade rounds of periodically fatal shelling and sniper fire.
Kiev and its Western allies have long accused Russia of orchestrating the conflict in reprisal for Kiev's decision to pull out of its historic orbit and forge a closer alliance with the European Union.
The new law also accuses Russia of "aggression" -- a charge the Kremlin denies despite overwhelming evidence of its soldiers and weapons crossing the border into the war zone.
It also hands over the reins of the eastern campaign to the army from the security service in line with other international armed conflict.
Ukrainian President Petro Poroshenko is set to sign the measure as he was the one who had submitted to parliament.
"We will continue to lay the groundwork for re-integrating the occupied Ukrainian territories through political and diplomatic means," Poroshenko tweeted after the 280-36 vote.
The seemingly symbolic change in the war's legal status in Ukraine came less than a month after the United States greenlighted its first delivery of anti-tank missiles to Kiev.
The powerful weapons are not expected in Ukraine for some months but have already seen Russia accuse Washington of fomenting fighting.
A senior rebel leader in east Ukraine and the head of the Russian Senate both said Kiev was violating the spirit of a tattered 2015 peace deal signed in the Belarussian capital Minsk.
"Unfortunately, this completely breaks the Minsk Agreements, contradicting them," separatist chief Alexander Zakharchenko told reporters in the rebel stronghold of Donetsk.
Russian Senate leader Valentina Matviyenko said the law showed that "Kiev was still trying to win back (the separatist east) through military means."
The Senate's s foreign affairs committee chairman Konstantin Kosachyov called the legislation "repugnant".
Kosachyov wrote on Facebook that Kiev was wiping out "all international efforts" to resolve the conflict.
The 2015 deal was brokered with the help of Germany and France. There was no immediate response from Berlin or Paris.
