As explained by DFRLab, while there are NATO troops and equipment in Poland and the Baltic states, Russia's Foreign Minister Lavrov’s claim that the presence increased in response to Zapad 2017 is misleading. The United States did, in fact, deploy three additional fighter jets and 600 American paratroopers to the Baltic states and Poland for the duration of Zapad. However, the deployment was public, reported by Reuters at the time, and there is no evidence to suggest that the additional forces overstayed their visit.
Similarly, the recent arrival of the 2nd Armored Brigade Combat Team (ABCT) to Poland, which was recently targeted by similar Kremlin disinformation, was a part of a planned rotation of U.S. Army Europe, a part of Operation Atlantic Resolve. As @DFRLab reported in October, the deployment of the 2nd Armed Brigade Combat Team was first announced in April 2017, six months before the start of Zapad 2017. There is no evidence to uphold the claim that the deployment was linked to Russia’s military exercise, but the deployment was rather a part of the rotational schedule. Further information at medium.com/dfrlab/balticbrief-russia-claims-secret-nato-deployment-e6c0e649ccfb,