By Robin Emmott and Phil Stewart
BRUSSELS (Reuters) - NATO was set on Tuesday to agree deployment of a new force in the Baltics and Poland, the last of a series of steps to deter a resurgent Russia but which some allies say must go further to be credible.
Three weeks before a critical NATO summit in Warsaw, the alliance's defense ministers will approve deployment of some 4,000 troops which, backed up by rapid reaction forces, could help deter a repeat of Moscow's show of force in Crimea elsewhere.
"We don't seek confrontation with Russia, we don't want a new Cold War," NATO Secretary-General Jens Stoltenberg said before the meeting in Brussels. He added: "NATO will continue to protect and defend all allies from any threat."
But while eastern allies welcome the deployments of four battalions of British, U.S., German and possibly Canadian troops 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.
That could involve NATO fighter planes and surface-to-air missile interceptors on a much larger scale in the Baltics.
Southern flank allies Bulgaria and Romania, meanwhile, are pushing for NATO to expand its maritime presence in the Black Sea, where Russia has a naval fleet, as well as more alliance troops to the region.
NATO aims to counter Russia's military build-up in Crimea, which Moscow annexed from Ukraine in 2014. The Black Sea is strategically important for both East and West given its energy reserves and closeness to the Middle East.
Stoltenberg said NATO was considering a Romanian offer to provide a brigade, typically around 5,000 troops, which could coordinate alliance training and possibly play a deterrent role. Defense ministers will discuss this on Tuesday, diplomats said.
Moscow 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.
"You don't invade with a few battalions, okay?" United States' 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."
The four battalions to be agreed on Tuesday are part of a wider NATO deterrent force to be approved in Warsaw in July. It will involve forces on rotation, warehoused equipment ready for an attack and a highly mobile "spearhead" force backed by NATO's 40,000-strong rapid reaction force.
The battalions will be under NATO command and deployed on a six-to-nine month rotating basis to the former Soviet states of Lithuania, Latvia, Estonia and Poland.
(Reporting by Robin Emmott; Editing by Richard Balmforth)