An exit from NATO by the United States, which is by far the largest contributor to the alliance’s military might, was so inconceivable before the Trump era that the NATO treaty actually requires any departing party to give notice to the United States. The alliance has struggled to spread the burden of defense equitably among members and adapt to the post–Cold War world, but an American withdrawal could precipitate the collapse not just of the defense bloc but also of the U.S.-European alliance, inviting Russian aggression in Europe and calling into question the United States’ alliances around the world.

Read: House Democrats want to investigate Trump’s foreign policy

Risch’s remarks, which amounted to a subtle drawing of a red line, also stood out because the senator from Idaho repeatedly defended Trump’s approach to Russia during our interview. Amid reports that Trump has concealed conversations with Russian President Vladimir Putin from even his closest advisers, and as Special Counsel Robert Mueller’s Russia investigation continues, Risch said that he does not plan to issue a subpoena to the U.S. government interpreters who attended the president’s meetings with Putin in Germany and Finland, or to hold hearings to shed light on what the U.S. and Russian leaders discussed in those one-on-one sessions, both of which his Democratic counterpart in the House is considering doing.

“The president of the United States, like every president before him, has had private conversations with heads of state,” Risch said, “and people who are authorized to engage in diplomacy … need to have the free hand to be able to conduct it as they see fit … I trust that President Trump did not take every word that Putin said as uttered in good faith.” (Trump has said that he believes Putin’s denial of meddling in the 2016 U.S. presidential election.)

On NATO, Risch didn’t commit to supporting proposed bipartisan legislation, which may be introduced in the new Congress, to prevent the president from ditching the alliance. (In the absence of such a law, which the White House could still fight in court, many legal scholars believe that the president has the authority to withdraw from NATO without consulting Congress.) “I don't want to go there yet,” Risch said, dismissing the prospect of a U.S. exit as mere “talk” and “speculation” at the moment. He (questionably) credited Trump with achieving through rough demands what he and other U.S. officials had long failed to accomplish with polite requests: European NATO members spending more on their own defense. But when I pointed out to Risch that he had once called NATO “the most successful military alliance in the history of the world,” he smiled. “That’s exactly right,” he said.

Risch oversees a 203-year-old committee with jurisdiction over everything from treaties and declarations of war to the president’s diplomatic nominees. And the positions he staked out on NATO and the Trump-Putin meetings are illustrative not just of how he may steer the committee, but also of how he and many other congressional Republicans appear to be compartmentalizing two distinct but interwoven issues: Russia as an adversarial actor abroad and Russia as a political minefield at home.