MOSCOW — Thousands of Russian troops began 10 days of military exercises in Belarus on Thursday, and Ukraine warned of upcoming Russian naval drills so extensive they would block shipping lanes, as the Kremlin continued to position forces in a way that left Ukraine vulnerable to a multipronged invasion.
In Moscow, Russia’s top diplomat, Foreign Minister Sergey V. Lavrov, gave a bleak assessment of the diplomatic efforts aimed at deterring a full-scale Russian attack, dismissing his talks with his British counterpart as a conversation of a “mute person with a deaf person.”
President Vladimir V. Putin of Russia was slightly more conciliatory, telling reporters that negotiations with the West were continuing over Russia’s demands to reshape the security architecture of Eastern Europe. He said Russia was preparing written responses in its back-and-forth with the United States and NATO, and added that he was planning to speak by phone in the coming days with President Emmanuel Macron of France.
But the intensifying Russian military activity north, east and south of Ukraine gave an ominous undertone to the diplomatic scramble. In Belarus, Ukraine’s northern neighbor and Russia’s closest international ally, Russian fighter jets launched air patrols, and Russia’s potent S-400 air defense systems were deployed near the Ukrainian border. Russian marines normally based in eastern Siberia — more than 2,500 miles away — practiced urban warfare, the Russian Defense Ministry said.
And off Ukraine’s southeastern coast, in the Black Sea and the Azov Sea, Russia was preparing to hold large-scale naval exercises — prompting a protest from Ukraine that they were blocking vital trading routes. Ukraine said the planned drills were “an abuse of international law” by Russia “in order to achieve its own geopolitical goals,’’ and it called on other countries to bar Russian ships from their ports.
Russia described all the drills as legal under international law, and promised that its troops would leave Belarus after the exercises there conclude on Feb. 20. But Western officials worry that the exercises could be a cover to position more Russian forces around Ukraine, giving Mr. Putin the ability to launch an invasion on short notice.
“This is a dangerous moment for European security,” Jens Stoltenberg, NATO’s secretary general, said, describing Russia’s military deployment to Belarus as its biggest since the end of the Cold War. “The warning time for a possible attack is going down.”
Gen. Mark A. Milley, the chairman of the U.S. Joint Chiefs of Staff, spoke by phone with his Belarusian counterpart, Maj. Gen. Viktor Gulevich on Thursday. The two discussed “regional security related issues of concern,” the Pentagon said in a brief statement, adding that it was intended partly “to reduce chances of miscalculation.”
Diplomatic efforts to resolve the crisis are scheduled to continue. Officials from Russia, Ukraine, Germany and France were set to meet in Berlin on Thursday in a recently revived four-way negotiating format centered on the conflict in eastern Ukraine, where the Kremlin is backing pro-Russian separatists.
Ben Wallace, the British defense minister, is expected to visit Moscow this week to meet his Russian counterpart. Next week, Chancellor Olaf Scholz of Germany is due in Moscow for talks with Mr. Putin. And President Emmanuel Macron of France has spoken several times with Mr. Putin, including in a five-hour meeting in Moscow this week.
Britain’s prime minister, Boris Johnson, said during a visit to NATO headquarters in Brussels on Thursday that he did not think Russia had made a decision on whether to launch an invasion. “But that doesn’t mean it is impossible that something absolutely disastrous could happen very soon indeed,” Mr. Johnson said.