"The Ukrainian authorities think they can use any means in order to defend their territorial integrity and sovereignty," Lavrov said.
Speaking to reporters in Moscow, Lavrov reiterated Moscow's belief that the Ukrainian government is the aggressor in the months-long battle, which in recent days has seen Ukraine regain control of a swath of territory in the east, forcing separatists to retreat to a handful of urban areas.
He portrayed the pro-Russia separatists as victims and said they were fighting for their survival.
"People in the east would otherwise be destroyed," he said. "That is the reason for the deterioration of the situation."
Ukraine and the U.S. believe that Russia is supplying ammunition and training to separatists, including heavy weaponry such as rocket launchers, and even firing from artillery positions on the Russian side of the border -- charges Russia has denied.
When questioned on the issue by a reporter, Lavrov on Monday pointedly did not deny that Russia was supplying weapons. Instead, he turned the discussion to monitors, saying that representatives from the impartial Organization for Security and Cooperation in Europe had been invited to the Russia-Ukraine border to witness military activity there, but had thus far not come. He said it was in fact Ukraine that was initiating shelling into Russia.
Lavrov also blamed Ukrainian military action for investigators’ inability to reach the crash site of Malaysia Airlines Flight 17, saying that a buffer zone announced by Ukrainian President
"The reality is Ukrainian authorities have to stop their fighting and respect the resolution of the U.N. Security Council and provide full access to the crash site," Lavrov said, adding that Russia wanted investigators to "find out the truth."
"The first priority is that the investigation will be impartial," he said.
Ukrainian officials said the separatists -- who Kiev and the U.S. believe fired the missile that downed the airliner -- have continued waging battle in the area, jeopardizing the safety of investigators hoping to find answers to the crash and recover property and human remains. U.S. and European officials have called on Russian President
On Sunday, a team of more than 60 Dutch and Australian investigators stopped short of reaching the site because of fighting nearby. They set out again Monday morning from the separatist-held city of Donetsk.
Lavrov also accused Kiev of violating a series of legal agreements after pro-Russia President
"The agreements have not been honored," Lavrov said, which has led to "a policy of suppression of protest in the east." He also said that "Ukrainian authorities are refusing to speak and sit at the negotiating table with the east and start the dialogue."
Poroshenko has said he is prepared to begin a legislative process to begin handing over more autonomy to Ukrainian citizens in the country's Russia-leaning east region.
Lavrov’s comments come at the start of a week when the
Lavrov said Russia would not necessarily retaliate if the EU voted in favor of harsher sanctions. "We are not intending to act on the principle of 'an eye for an eye,'" he said.
But he decried the sanctions as unfair.
"The Western partners have not explained what they want from us," he said. "Just saying Russia needs to change is not enough."
Staff writer Zeitchik reported from Kiev, and special correspondent Gorst reported from Moscow