Armed pro-Russian separatists secure the site of an explosion in front of the regional government building in Donetsk June 12, 2014. A bus of Denis Pushilin, senior member of the separatist rebellion leadership, exploded and left four personnel wounded, according to a statement of the self-proclaimed Donetsk People's Republic. REUTERS/Shamil Zhumatov

The Ukrainian government says Russia allowed three tanks and other military assets to cross the border from Russia into eastern Ukraine, where fighting between separatists who wish to join Russia and the Ukrainian military continues.

Ukraine’s Interior Minister Arsen Avakov says the assets crossed at a border crossing controlled by eastern separatists. The vehicles headed to different parts of the east, but the Ukrainian military had confronted and destroyed “part” of a column in Donetsk. Avakov did not say Russia sent the equipment in themselves, but did place blame on Russian President Vladimir Putin for failing to secure the Russian-Ukrainian border.

According to Reuters, correspondents who spotted two tanks in Snizhne, a town about 10 miles from the Russian border, said there were no markings to identify the tanks as either Russian, Ukrainian or otherwise.

Ukraine’s newly elected president, Petro Poroshenko, called President Putin to tell him the movement was “unacceptable.”

The Russian foreign ministry called the accusation “another fake piece of information.” Russia has strongly maintained it has no interest in sending troops into eastern Ukraine.

Speaking of the conflict as a whole, Russian Foreign Minister Sergei Lavrov told Russian media that he does not believe it is time for Russia to send in “peacekeepers” to Ukraine. He placed responsibility on President Poroshenko to put an end to violence in the country.

“… hope still exists that President Poroshenko’s statement on the end of the violence and beginning of the negotiations will come into force since Poroshenko still maintains trustworthiness and it can be used now… Everything is in the hands of Ukrainian authorities,” Lavrov said.

In the nearby city of Donetsk, Denis Pushilin, the self-proclaimed leader of the Donetsk People’s Republic (DPR), told Russian newspapers that his bus was blown up Thursday night. Four people were wounded, at least two of them seriously, in the explosion. The DPR says it happened 100 meters away from the self-proclaimed DPR’s administrative headquarters.

“My car was blown up. There were three people inside, two of them are in serious condition,” Pushilin said. “I have not ridden in the car for two days.”

The attack appears to be the second attempt on his life in the last week. One of Pushilin's aides, Maxim Petrukhin, was shot and killed in Donetsk on June 7. The prime minister of the DPR says that the two men resemble each other and that Pushilin could have been the intended target.

Pushilin says he has his suspects, including the Ukrainian government.