In a move to reassure Russia’s neighbors, the United States will send some 600 paratroopers to Poland and the Baltics starting tomorrow as part of an open-ended military commitment prompted by Moscow’s actions in Ukraine.

“I can announce today that a company-size contingent of paratroopers from the U.S. Army Europe's 173rd Infantry Brigade Combat Team airborne, which is based in Vicenza, Italy, will arrive in Poland tomorrow to begin exercises with Polish troops,” Rear Admiral John Kirby, a Pentagon spokesman, told reporters at his daily briefing.

Poland, Estonia, Latvia and Lithuania will get 150 American troops each. The full deployment will be complete “by the end of this weekend, maybe Monday,” Kirby said.

Even when those U.S. forces rotate back, new ones will take their place for new exercises throughout the rest of 2014, “but beyond that, it could go beyond the end of this year," Kirby said. "We just don't know. We're just going to have to see how it goes.”

And the exercises “very well could” expand to other NATO allies, Kirby said. “But right now it's going to start with those four countries.”

“Since Russia's aggression in Ukraine, we have been constantly looking at ways to reassure allies and partners,” he said. “These exercises were conceived and added onto the exercise regimen as a result of what's going on in Ukraine.”

Kirby underlined that one goal of the deployment was to highlight the U.S. commitment, under Article 5 of the NATO charter, to treat an attack on a member of the alliance as an attack on the United States itself.

“The message is to the people of Poland and Lithuania, Latvia, Estonia that the United States takes seriously our obligations under Article 5 of the NATO alliance even though these aren't NATO exercises,” he said.

“And I think if there's a message to Moscow, it is the same exact message, that we take our obligations very, very seriously on the continent of Europe,” Kirby said. “The kind of work that we're going to be doing is real infantry training. And that's not insignificant.”

The deployment could be large enough to reassure American allies nervously watching Russia, which gobbled up Ukraine’s strategic Crimean peninsula after a pro-Western government seized power in Kyiv and has hinted at broader designs on Ukrainian territory. But it also appears to be small enough that Moscow will not regard it as an escalation.

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