Marco Rubio takes Rex Tillerson to the woodshed over Russia.

President-elect Donald Trump has a serious Russian problem with many sides to it. He wants to have friendlier relations with Vladimir Putin’s Russia but it’s not clear that his party is onboard. In the background to this policy dispute are allegations, circulating in the intelligence community and press, that the Trump campaign benefited from Russian assistance in the election. The potential fissure between Trump and the GOP started to burst open in the hearings this morning to confirm Rex Tillerson, the former Exxon Mobile CEO, as secretary of state.

Marco Rubio took the lead in grilling Tillerson, asking if Vladimir Putin is “a war criminal.” Tillerson responded, “I would not use that term.” Rubio responded with a grandstanding oration describing Russian targeting of civilians in Syria and Chechnya. Rubio concluded that he found Tillerson’s “inability” to use the term war criminal “discouraging.” The exchange makes clear that, along with fellow Senators Lindsay Graham and John McCain, Marco Rubio could become one of the leaders of a hawkish senatorial faction within the Republican Party that will make Donald Trump’s foreign policy agenda hard to achieve, starting with hurting Tillerson’s credibility.