There is widespread concern that Russia and other countries have launched social media campaigns designed to increase political polarization in the United States. Though a growing number of studies analyze the strategy of such campaigns, it is not yet known how these efforts shaped the political attitudes and behaviors of Americans. We study this question using longitudinal data that describe the attitudes and online behaviors of 1,239 Twitter users from late 2017 merged with non-public data about the Russian Internet Research Agency from Twitter. Using Bayesian Regression Tree Models, we find no evidence that interaction with Internet Research Agency accounts substantially impacted six distinctive measures of political attitudes and behaviors. We also find that overall levels of interaction with Internet Research Agency accounts were low, and most common among respondents with strong ideological homophily within their Twitter network, high interest in politics, and high frequency of Twitter usage. Together, these findings indicate Russian trolls might have failed to sow discord because they mostly interacted with those who were already highly polarized. We conclude by discussing several important limitations of our study as well as its implications for future research on misinformation campaigns on social media, political polarization, and computational social science.