On Sunday, Germany announced that the leaders of Russia, Ukraine, Germany and France aimed to meet in Minsk on Wednesday to continue work on resolving the Ukraine crisis. Diplomats will gather in Berlin on Tuesday to try to arrange the meeting, the German government spokesman, Steffen Seibert, said in a statement.

Speaking in Sochi during a meeting with the leader of Belarus, President Vladimir V. Putin of Russia said that a Wednesday meeting would require agreement on key points beforehand. “We will be aiming for Wednesday, if by that time we are able to agree on a number of points that we’ve recently been discussing intensely,” he said.

At the conference, sharp splits emerged between Germany and prominent American politicians like Senator John McCain over the wisdom of supplying defensive arms to Ukraine. Moscow continues to deny the involvement of its military. But one of the main prompts for Germany and France to try to work out a new arrangement in eastern Ukraine has been a serious discussion in Washington about providing lethal, if defensive, military equipment to Kiev, something that both the German and French leaders have opposed.

In a speech on Sunday, Mr. McCain said the European opposition missed the connection between military pressure and successful diplomacy. “If we help Ukrainians increase the military cost to the Russian forces that have invaded their country, how long can Putin sustain a war that he tells his people is not happening?” he said. “That is why we must provide defensive arms to Ukraine.”

He said that in his view, Mr. Putin did not want a diplomatic solution, but “he wants to dominate Ukraine” as a “prelude to further aggression.”

The German foreign minister, Frank-Walter Steinmeier, brushed away the criticism. Negotiations for a peaceful solution are vital, he said. “We must make sure we use this opportunity to contain and then defuse these conflicts,” he said. “It would be irresponsible not to use the opportunities we have.”