Britain, Germany and the United States advanced plans on Tuesday to spearhead a new NATO force on Russia's border from next year, and Russian President Vladimir Putin ordered snap checks on combat readiness across his armed forces.
Weeks before a critical NATO summit in Warsaw, three of NATO's biggest military powers said they would each command a battalion across the eastern flank to help deter any show of force such as that deployed by Moscow in Crimea in 2014.
"Britain will lead one of the battalions," British Defense Secretary Michael Fallon said at a meeting of NATO defense ministers, adding London will send up to 700 troops to the Baltics and Poland.
"That should send a very strong signal of our determination to defend the Baltic states and Poland in the face of continued Russian aggression," he said.
In a reminder of Russia's efforts to bolster its military readiness, its armed forces started carrying out spot checks on its units, as well of weapon and equipment depots.
Russian Defense Minister Sergei Shoigu said the goal of the June 14-22 drill was to ensure the ability of his military to "carry out planned activities, including mobilization."
NATO's battalions are part of a wider deterrent to be approved at the Warsaw summit on July 8. It will involve troops on rotation, warehoused equipment and a highly mobile force backed by NATO's 40,000-strong rapid reaction unit.
NATO hopes the complex plan can discourage Russia from orchestrating the kind of campaign used to annex Ukraine's Crimea peninsula in February 2014 and which has left eastern allies nervous of their former Soviet overlord.
Berlin and Washington also said that they would send troops to the new force, which is expected to total about 4,000 soldiers, with contributions from other allies. France is sending a company of about 250 troops to Britain's battalion.
Germany is likely to deploy to Lithuania, the United States to Poland and Britain to Estonia, on a six- to nine-month rotating basis. Other NATO nations will eventually take command responsibilities, diplomats told Reuters.
Canada announcement soon?
Western officials also acknowledged discussions in Canada to lead a fourth battalion, with a British official saying a decision could come as early as Wednesday. Reuters first reported on Canada's possible role last week.
Canada's battalion was expected to be based in Latvia, diplomats say, although Ottawa has yet to comment publicly.
The new deployments are apart from U.S. plans to provide an armored brigade, typically around 5,000 troops, plus extra equipment in Europe.
"There will be a continually present armored brigade combat team, which will bring in its own equipment with each rotation," said U.S. Defense Secretary Ash Carter. He said that on top of that, the United States would bring "a pre-positioned set of equipment for yet an additional armored brigade combat team which troops could fall in upon in a crisis."
While eastern allies welcome the deployments in NATO's biggest military build-up since the end of the Cold War, they want more support to defend against Russia's powerful arsenal.
With a warning last week from a senior U.S. commander that the alliance would have only 72 hours notice of a missile or ground attack, Baltic nations and Poland want a sophisticated anti-missile shield to deter Russia from gaining the upper hand.
NATO Secretary-General Jens Stoltenberg said NATO was also considering a Romanian offer to command a multinational brigade which could coordinate alliance training and possibly play a deterrent role.
Russia sees NATO's deterrence plans as hostile. Moscow's envoy to the alliance has warned they threaten peace in central Europe. The Kremlin also says a U.S. ballistic missile shield, which Washington says is directed at protecting the alliance from Iran, is also escalating tensions.
The United States denies that. NATO says it is respecting a 1997 agreement with Moscow not to deploy substantial combat forces on Russia's borders.
"You don't invade with a few battalions, okay?" the U.S. envoy to NATO, Douglas Lute, told reporters. "But you can deter, and you can affect a potential aggressor's calculus in terms of cost, benefit and risks."