BRUSSELS — NATO foreign ministers moved Tuesday to beef up the defenses of front-line alliance members feeling menaced by a more assertive Russia, with Secretary of State John F. Kerry proclaiming the US commitment to their security is ‘‘unwavering.’’
The ministers from NATO’s 28 member nations also ordered suspension of all ‘‘practical civilian and military cooperation’’ with Vladimir Putin’s Russia, though they made sure a line of communication with the Kremlin remains open at the ambassadorial level.
The North Atlantic Treaty Organization, keystone of US and European security since the end of World War II, is facing its most acute geopolitical crisis in years: the fallout from Moscow’s unilateral annexation of Ukraine’s Crimean Peninsula, which the Obama administration and its allies condemn as a brazen, illegal land grab.
On Tuesday, an estimated 35,000 to 40,000 Russian troops equipped with tanks, other armored vehicles, and fixed and rotary wing aircraft remained positioned near the border with Ukraine, a NATO military official told the Associated Press, speaking on condition of anonymity because of the sensitive nature of the information.
The military official described the Russian buildup as ‘‘a complete combat force’’ that was highly threatening to Ukraine.
Those troops, and future aggressive moves that Putin’s Kremlin may make, have become a troubling concern for NATO countries, especially the alliance’s eastern-most members — the Baltic states, Poland, and Romania, all of which were once in Moscow’s orbit.
To reassure those skittish allies, Kerry told a news conference, the United States has already sent six F-15 fighters to perform air patrols over the Baltic, deployed a dozen F-16s to Poland, and dispatched the USS Truxtun, a guided-missile destroyer, to the Black Sea.
‘‘And more US support is on the way,’’ Kerry said.
At the Tuesday afternoon meeting he attended with the foreign ministers, Kerry said, ‘‘more allies pledged their own contributions to make sure every ally from the Baltic to the Black Sea feels secure.’’
Despite annexing Crimea, Putin and other officials have said that Russia has no intention of invading other areas of Ukraine. Defense Minister Sergei Shoigu insisted Tuesday that the Kremlin wants a ‘‘political settlement that would take interests and rights of the entire Ukrainian people into account.’’