MUNICH — Russia’s prime minister accused NATO on Saturday of restarting the Cold War amid increased military maneuvers and troop deployments to countries neighboring Russia, moves the alliance’s top official defended as a necessary response to aggression from Moscow.

Prime Minister Dmitry Medvedev of Russia told a meeting of top defense officials, diplomats, and national leaders that sanctions imposed after Russia’s 2014 annexation of Crimea and new moves by NATO “only aggravate’’ tensions.

“NATO’s policies related to Russia remain unfriendly and opaque — one could go so far as to say we have slid back to a new Cold War,’’ Medvedev said. “On almost a daily basis, we’re called one of the most terrible threats either to NATO as a whole, or Europe, or to the United States.’’

The comments came after NATO Secretary-General Jens Stoltenberg told the Munich Security Conference that “Russia’s rhetoric, posture, and exercises of its nuclear forces are aimed at intimidating its neighbors, undermining trust and stability in Europe.’’

Later, Stoltenberg said in an interview that all of NATO’s moves had been made in response to Russian aggression.

“NATO does not seek confrontation and we do not want a new Cold War. But we had to respond to the Russian military buildup, which we have seen over several years,’’ he said. “Not only a military buildup, but the fact that Russia is willing to use military power to change borders in Europe as they have done in Ukraine.’’

The annual conference in Munich is one known for frank talk among top officials.

Speaking after Medvedev, Secretary of State John Kerry fired back that Europe and the United States would continue to “stand up to Russia’s repeated aggression’’ and noted that in addition to a joint focus on Ukraine, Washington plans to quadruple spending to help European security. That will allow the United States to maintain a division’s worth of equipment in Europe and an additional combat brigade in Central and Eastern Europe.

NATO also announced last week it would add new multinational reinforcements to beef up defenses of front-line alliance members most at risk from Russia.

“Those who claim our trans-Atlantic partnership is unraveling — or those who hope it might unravel — could not be more wrong,’’ Kerry said.

Stoltenberg stressed the need for dialogue but also defended NATO’s move to strengthen defenses, including moving more troops and equipment to countries bordering Russia. He said at a summer summit in Warsaw he expects NATO members “to decide to further strengthen the alliance’s defense and deterrence.’’

He said it was also a positive “first step’’ that NATO members have mostly stopped cuts to their defense budgets and were working toward NATO’s expectation that its members spend 2 percent of GDP on defense — a goal few meet.

President Petro Poroshenko of Ukraine blasted Russia’s actions in both Ukraine and Syria, saying they are “a demonstration that we live in a completely different universe’’ from Russia.

He said the main danger to Europeans now is an “alternative Europe with alternative values’’ such as isolation, intolerance, and disrespect for human rights. Poroshenko added: “This alternative Europe has its own leader. His name is Mr. Putin.’’