The Obama administration is hearing growing calls to permanently station a substantial number of troops in Eastern Europe as a deterrent to Russian President Vladimir Putin. Putting a large number of U.S. or NATO troops in Eastern Europe would violate a 1997 treaty with Russia, but those arguing for the placement say Putin already broke that treaty by backing the takeover by Russian-backed groups of Ukrainian territory. Sen. John McCain (R-Ariz.), chairman of the Senate Armed Services Committee, said he doesn’t think the United States should honor any agreement with Russia. But he also said he thinks the rotational deployments are sufficient.