On Wednesday, the day after Iran retaliated for the strike on Soleimani, the campaign sent around a statement saying “Bernie Sanders can’t be trusted to defend American lives.” The following day, it released a statement attacking the candidate more broadly, calling him a “wealthy fossil fuel-guzzling millionaire.”

“Bernie Sanders is dangerous,” Trump’s campaign spokesperson Tim Murtaugh told BuzzFeed News. “He believes that taking out the most vicious terror chief on the planet sets a bad ‘precedent’ and he uses the same talking points as the Iranians and Russians by calling it an ‘assassination.’ He cannot be trusted to keep Americans safe.”

Since entering the race this spring, Sanders has positioned himself in competition with Trump as much as with his Democratic rivals. In his pitch in Iowa and Midwestern states like Ohio and Michigan, Sanders has contended that he is the candidate who can peel away disaffected voters from the president in a general election, hosting events like a “Bernie Beats Trump” tour through Iowa counties that flipped from Barack Obama in the 2012 election to Trump in 2016.

The Sanders campaign said the shift by Trump signaled new concern.