NATO and Russia held more than three hours of talks on Monday, discussing ways to reduce military accidents but also underscoring their deep disagreement on the conflict in Ukraine.
Western diplomats said the fact that the NATO-Russia Council, where the Russian ambassador to the North Atlantic alliance sits with members states' envoys, had met at all was significant after an increase in Russian military deployments.
"Without talking, we cannot solve our differences," NATO Secretary-General Jens Stoltenberg said after the meeting in Brussels.
Russia has alarmed NATO by equipping its Baltic fleet with nuclear-capable missiles and stepping up Cold War-style aerial incursions to probe Western air defenses. In October, it demonstratively sent its sole aircraft carrier close to Europe's shores on its way to Syria.
Russian Ambassador Alexander Grushko gave a detailed briefing on Russian military exercises involving around 120,000 personnel in recent months, NATO diplomats said.
There was also discussion in Brussels of the tactics being used by Russian pilots, which NATO says are unsafe. These include flying barrel rolls over Western aircraft, not sharing flight plans, and flying without the transponders that allow jets to be identified by ground radar.
But Stoltenberg said there continued to be "profound disagreements" on one of the central issues in East-West relations: Ukraine.
He said NATO members would not recognize Russia's annexation of Crimea from Ukraine in 2014, and that the alliance remained deeply concerned about eastern Ukraine, partly controlled since 2014 by rebels whom NATO accuses Moscow of financing.
Despite an internationally-monitored cease-fire, diplomats have cited increasing reports of shelling and civilian casualties.
NATO for its part has responded to increased Russian military activity by planning to deploy troops to the Baltic states and Poland next year. Although it says its plans are defensive, Russia has been irked and sought explanations.
Separately, Ukrainian Europe Minister Ivanna Klympush-Tsintsadze, who met EU officials in Brussels, told Reuters six Ukrainian soldiers had been reported killed on Monday and another 26 wounded in shelling by Russian-backed rebels.
The EU extended economic sanctions against Russia on Monday due to a lack of progress in implementing the Minsk cease-fire deal, under which a cessation of fighting was due to be followed by Kyiv agreeing to hold local elections in the region.
"The ball is in the Russian court," Klympush-Tsintsadze told Reuters. "Without security guarantees, without a cease-fire holding... it will be impossible for Ukraine to move on the political agenda."