Pro-Russian Ukrainian separatists shot down four government fighter jets in the Donetsk region Friday, the Russian state-owned Itar-Tass news agency reported. The same day, the United Nations said 2,593 people have been killed in fighting in eastern Ukraine since in mid-April.

“The trend is clear and alarming,” Ivan Simonovic, U.N. assistant secretary-general for human rights, said in Kiev, according to Reuters. “There is a significant increase in the death toll in the east.”

Less than two weeks ago, separatists shot down another Ukrainian fighter plane, the Associated Press reported. A Ukrainian military representative said that plane was shot down over the Luhansk region after launching an attack on separatists.

President Barack Obama said Thursday there would be no U.S. military action in Ukraine. “I think it is very important to recognize that a military solution to this problem is not going to be forthcoming,” Obama said during a press conference at the White House. When asked by a reporter whether he would describe the escalating Ukraine crisis as an invasion by Russia, the president replied:

I consider the actions that we’ve seen in the last week a continuation of what’s been taking place for months now. ... The separatists are backed, trained, armed, financed by Russia. Throughout this process, we’ve seen deep Russian involvement in everything that they’ve done.

Obama added, “My expectation is, is that we will take additional steps primarily because we have not seen any meaningful action on the part of Russia to actually try to resolve this in diplomatic fashion.”