Reports of Russian military vehicles crossing into Ukraine continue to appear online; however, Ukraine has now confirmed that Russian APC's entered Ukrainian territory and were fired upon.

In a statement published on his website, Ukrainian President Petro Poroshenko confirmed that Russian armored personnel carriers had crossed into Ukraine, and "much of this equipment was destroyed by the Ukrainian artillery at night,” according to USA Today.

News about the Russian APC’s first surfaced thanks to Shaun Walker and Roland Oliphant, from the Guardian and the Daily Telegraph, respectively, who first reported the Russian movements on Twitter as they followed the Russian humanitarian aid convoy. However, it has not been confirmed if the vehicles are operated by the Russian military.

However, Russia denied its vehicles or troops have crossed the border, the Guardian reported. The Russian FSB, successor to the KGB, claimed the vehicles were sent to the border to ensure safety and “prevent the infiltration of armed people on the territory of the Russian federation”.

Yet, the news of possible Russian movements into Ukraine has alarmed European leaders. U.K. Foreign Secretary Philip Hammond warned Russia against invading Ukraine.

“I’m very alarmed by reports that Russian military vehicles may have crossed the border this morning. If there are any Russian military personnel or vehicles in eastern Ukraine, they need to be withdrawn immediately,” he said.

Reuters reported that Russia's Defense Ministry denies the Ukrainian allegations, calling them “some kind of fantasy.” However, Andriy Lysenko, a spokesman for the Ukrainian military, said at a press briefing that Russian vehicles did attempt to cross the border at night.

"Appropriate actions were undertaken, and a part of it no longer exists," Lysenko said of the advancing column. 

The New York Times added that NATO secretary-general, Anders Fogh Rasmussen, confirmed the “incursion” of Russian vehicles.