Russian President Vladimir Putin’s op-ed in the New York Times warning the U.S. not to strike Syria rattled both Republicans and Democrats on Capitol Hill and raised doubts Moscow could be an honest broker in talks over securing international control of Damascus’ chemical arsenal.

House Speaker John Boehner, R-Ohio, on Thursday said he was “insulted” by Putin’s comments, and said he had “real doubts” about Russia’s ability to successfully broker a deal turning over Syria’s chemical weapons to international inspectors to avert a threatened U.S. strike.