Note:
(a) In US, made up of of 17,000 to 21,000 soldiers and commanded by a major general, a division consists of three maneuver brigades and an aviation brigade.
Division (military) https://en.wikipedia.org/wiki/Division_(military)
(section 4.11 United States)
(b) "to start in February 2017"
"among six eastern members [of NATO]—Lithuania, Estonia, Latvia, Poland, Romania and Bulgaria."
"Russian officials argue the decision violates the 1997 NATO-Russia Founding Act, a document that says the alliance won't position substantial, permanent combat forces on Russia's borders." US disagree, insisting the forces to be deployed is not substantial.
Wall Street Journal (available online now but) to be in print tomorrow (Mar 31).
(c) NATO https://en.wikipedia.org/wiki/NATO
(section 3 Participating countries)