United Nations Secretary General Ban Ki-moon criticized the election held in eastern Ukraine by pro-Russian separatists, calling the act an "an unfortunate and counterproductive development." The elections violated terms of the treaty signed by Ukraine and pro-Russian rebels signed in September.

"I urge all concerned to urgently recommit to full implementation of the letter and spirit of the Minsk Protocol and Memorandum, designed to bring peace and stability to all of Ukraine. In addition to the tragedy of lost lives both on land and in the sky, the crisis risks jeopardizing our collective ability to solve global problems," Ban said in a statement.

Russia announced it will recognize the results of Sunday's elections, which created further tension with Western governments that have accused Moscow of supporting rebels against Ukraine. In Sunday's polls, Aleksandr Zakharchenko was elected head of the self-proclaimed Donetsk People's Republic and Igor Plotnitsky was elected to head the self-proclaimed Luhansk People's Republic. Zakharchenko was sworn in Monday.

The polls have been denounced by the U.S., the European Union and Ukraine President Petro Poroshenko. The elections were "a farce, (conducted) under the barrels of tanks and machine guns," Poroshenko said following the announcement of the results.

As part of the Minsk protocol, elections held in Donetsk and Luhansk would be run by Ukraine in December, the BBC reported. The treaty was meant to deescalate the conflict in eastern Ukraine and included a planned 18.6-mile-wide buffer zone. Despite the cease-fire agreement, fighting continued in the area, including several attacks on the Ukraine-held Donetsk Airport. After the election, a convoy of 40 trucks carrying military equipment and troops were seen entering the country.

"There is intensive deployment of military equipment and personnel of the enemy from the territory of the Russian Federation onto territory temporarily controlled by insurgents," Ukrainian military spokesman Andriy Lysenko said in a briefing Monday. Russia has denied assisting the rebels in the Ukraine Crisis, which has seen more than 4,000 people killed and over 375,000 people displaced according to a U.N. report.