The situation in Ukraine worsens: President Petro Poroshenko has announced Ukraine has been invaded by Russian troops at the southern town of Novoazovsk, where pro-Russia rebels opened a new front with Russian help.

Rebel troops have expanded the frontline, stretching Ukrainian troops and weakening their resolve and momentum; however, they are not doing it alone. The Ukrainian government contends Russia has tipped the balance of the conflict in favor of the separatists by providing military support, according to The New York Times.

As a result, both Ukraine’s President Poroshenko and its prime minister, Arseniy Yatseniuk, have condemned Russia’s actions and have asked their European and American allies for further help, reports the Los Angeles Times. Poroshenko canceled a trip to Turkey and called an emergency meeting of his security council on Thursday.

These new developments derail any peace prospects, which began to slowly blossom during a meeting between Poroshenko and Russian President Vladimir Putin in Belarus earlier this week.

The Los Angeles Times reports that Aleksandr Zakharchenko, prime minister of the self-declared Donetsk Peoples Republic, appeared on Russian state TV and claimed between 3,000 and 4,000 Russian volunteers were fighting alongside the rebels.

“They are fighting with us, understanding that it is their duty,” he said, adding that some had died fighting for the cause. A revelation of Russian involvement and casualties in the conflict by a separatist leader rebuts Russia’s continued denial of its involvement in the conflict.

However, The New York Times reported that the invasion of the border town of Novoazovsk, some 75 miles south of Donetsk, could be a tactic by Russia to divert attention and Ukrainian military resources from the battlefronts of Donetsk and Luhansk. With the frontline stretched to the Sea of Azov, the Ukrainian military will have a harder time fighting the rebels emboldened by Russian support.

Though Russia continues to deny its involvement in the fighting, retreating Ukrainian troops in the south say the forces they encountered were Russian simply disguised as separatist. Both the U.S. and NATO have photographic evidence and intelligence of Russian movements within Ukraine, including artillery positions.

In Novoazovsk, tanks and armored personnel carriers drove through the town painted in rebel colors and flying rebel flags; however, according to The Interpreter, an online publication that translates and monitors Russian media, a video showing the armored column depicts a tank only used by Russia.

The T-72 tanks that appear in the footage are not used by the Ukrainian military and could not have been captured by rebel forces from Ukrainian army bases, reports The Interpreter

John Dempsey, an analyst at the International Institute for Strategic Studies (IISS) confirmed to BBC News that, while three T-72s models have been sold abroad, the Russian army exclusively operates the T-72BM with explosive reactive armor, characterized by box-like additions on the turret. The appearance of this tank proves Russia’s involvement in the fighting or that it is supplying weapons to the rebels.