Ukraine President Petro Poroshenko met with European Union officials in Brussels Saturday to discuss his country’s current conflict and new sanctions against Russia following “direct aggression by Russian forces,” BBC News reported. Russia President Vladimir Putin has denied his nation is either involved in eastern Ukraine or has provided pro-Russian separatists with armored vehicles or training.

The EU could impose new economic sanctions in an attempt to prevent further Russian involvement in Ukraine, according to the Associated Press. During the meeting Saturday, European Commission President Jose Manuel Barroso said, “Ukraine now is a subject for foreign military aggression and terror,” CNN reported.

If the EU chooses to implement new economic sanctions, it would be the third round of such penalties for Russia. Most recently, it and the U.S. imposed sanctions against Russia targeting the defense, energy and finance industries. Russia responded to the move by establishing a food import ban. And a while back, the EU and the U.S. issued sanctions against Russia following its annexation of Crimea.

NATO has denied Russia’s claims that it has not been involved in the Ukrainian conflict, saying: “Russian forces are engaged in direct military operations inside Ukraine. Russia continues to supply the separatists with tanks, armored vehicles, artillery and rocket launchers.” NATO also provided satellite images showing Russian forces inside Ukraine, which is currently seeking NATO membership. NATO said 1,000 Russian troops are supporting separatists in eastern Ukraine, reports AP.

Putin warned Friday against any aggression on the part of Western governments. “We must always be ready to repel any aggression against Russia, and our partners should always be aware that no matter in which condition their governments may be or which foreign-policy concepts they may pursue, it is better not to come against Russia as regards a possible armed conflict,” the Russian president during an appearance at a pro-government youth camp.