Behind the numbers: Pew has shifted wording on its questions about Russia over the years, depending on relevant foreign policy issues. In 2005, 2006, 2008, 2013 and 2015, respondents were asked their views on "growing authoritarianism in Russia." In 2009 and 2013, they were asked about "growing tensions between Russia and its neighbors." Respondents were asked about "tensions with Russia" in 2016 and "Russia's power and influence" in 2017.

Key takeaways:

• Democrats and Republicans generally agreed on whether Russia posed a threat to the U.S. until the Trump era.
• In the full pool of respondents, 52% said Russia is a major threat and 38% called it a minor threat.
• Per the report, 46% of Americans think China poses a major threat; 59% say so about climate change; 68% feel threatened by ISIS.
• The share of Americans who see ISIS as a threat has dropped from 83% in 2015 to 68% this year.
• A significantly larger portion of respondents feel threatened by North Korea's nuclear program (75%) compared to Iran's program (53%).