NATO Secretary-General Jens Stoltenberg has described relations with Russia as hitting a new low following a fresh spat that saw Kremlin envoys to the alliance stripped of accreditation and NATO's office in Moscow due to close.
"It has not been more difficult since the end of the Cold War," Stoltenberg said ahead of a two-day summit of defense ministers in Brussels beginning on October 21.
Earlier this month, NATO expelled eight Russians accredited to the alliance, saying they were intelligence agents. NATO also halved the number of accredited positions for Russia to 10.
Russia responded by suspending its mission at NATO and ordering the closure of the alliance’s office in Moscow, accusing it of not wanting dialogue and failing to provide proof about the alleged spying.
"We still have avenues and channels for communications with Russia, but we regret the Russian decision to close the two NATO offices in Moscow, and to also stop their activity at that NATO mission here at NATO," Stoltenberg said.
"NATO's approach to Russia remains the same as before, meaning credible deterrence and defense, combined with efforts to have a meaningful dialogue with Russia," he added.
German Defense Minister Annegret Kramp-Karrenbauer said that the Russian mission to NATO had carried out intelligence activities under the cover of their diplomatic status. "This isn't new behavior," she said.
The main forum for dialogue between the two sides -- the NATO-Russia Council -- has met only sporadically since 2014.
The latest dispute between NATO and Russia isn't on the summit's agenda in Brussels, where defenses ministers are expected to discuss a so-called "master plan" to defend the alliance against any potential Russian attack.
The 30 alliance members are also to discuss other top concerns, including shared deterrence and defense strategy, common concerns about the rise of China, investment in new technologies, and the process of evaluating the "lessons learned" in Afghanistan.
The Concept for Deterrence and Defense in the Euro-Atlantic Area, as the master plan is known, is confidential, but Reuters quoted unidentified officials and NATO diplomats as saying it goes beyond existing regional defense plans, aiming to prepare for any simultaneous attack in the Baltic and Black Sea regions.
The new plan is needed as Russia develops advanced weapon systems and deploys troops and equipment closer to the borders of NATO member states, the officials said.
Russia denies any warlike intentions and says NATO is the one that risks destabilizing Europe with such preparations.
"This is the way of deterrence," Kramp-Karrenbauer said of the plan.
"And this is being adapted to the current behavior of Russia -- and we are seeing violations particularly of the air space over the Baltic states, but also increasing incursions over the Black Sea," Kramp-Karrenbauer told German radio.
Her British counterpart, Ben Wallace, told reporters that the plan "recognizes a more 21st-century threat and how to deal with it."
In May, Russia amassed some 100,000 troops on its border with Ukraine, the highest number since Moscow forcibly annexed Crimea in 2014 and stoked conflict in eastern Ukraine, according to Western officials.
Russia used new combat robots in large military drills with Belarus in September that have alarmed Baltic allies.
Russia is also upgrading or replacing Soviet military space systems to potentially attack satellites in orbit and is developing "super weapons” that include nuclear-capable hypersonic cruise missiles that could evade early-warning systems.
NATO is also concerned over Russia's aerial intrusions into NATO airspace and the buzzing of allied vessels by Russian fighter planes and warships.
On Afghanistan, Stoltenberg said the ministers were still evaluating lessons learned after the Taliban seized control of Kabul from the internationally recognized government in mid-August following a blitz offensive amid a hasty withdrawal of U.S.-led forces that put an end to the 20-year war.
The ministers will be looking at how the limited mission of fighting terrorism became a larger nation-building effort, the secretary-general said.
"The lesson-learned process has to focus on both what did not work, but also what worked, because it is of course a tragedy for the Afghan people, that Taliban is back, it's heartbreaking for all of us who supported Afghanistan for so many years, but at the same time we should recognize that we actually made significant achievements," he said.
"Our mission was not in vain -- we prevented Afghanistan from being a safe haven for international terrorists, and prevented any attack against any NATO ally over 20 years," he noted. "Now we will stay vigilant and preserve those gains. Not least by holding, using the leverage we have on the new Taliban regime to make sure that they live up to their commitments on terrorism, on human rights, and safe passage."
NATO took the lead on international security efforts in Afghanistan in 2003 but ended combat operations in 2014 to focus on training and advising Afghan security forces. It helped build up a national army of some 300,000 troops that withered in August in the face of the Taliban offensive.
More than 123,000 foreigners and at-risk Afghans were airlifted from Kabul airport during the final days of the U.S.-led military presence, after President Joe Biden said U.S. troops would leave by August 31.