It’s not every day that Republican legislators feud on social media, let alone accuse one another of sympathizing with terrorists. But that’s exactly what happened on Thursday afternoon, during a Twitter feud about foreign policy between the libertarian-leaning Rand Paul and the hawkish Liz Cheney.

It all started when Paul, a Kentucky senator, shared a Washington Examiner op-ed that was critical of Cheney’s stance on Afghanistan. He called her a “neocon” who advocates for “endless wars.” Cheney, a Wyoming congresswoman and daughter of former Vice President Dick Cheney, blasted Paul in response, which prompted Paul strategist Doug Stafford to get involved.

This entire feud is regrettable. But Cheney’s subsequent escalation is classless and out of bounds. Paul started this with a valid, if antagonistic, critique of her foreign policy. She responded by impugning his motives and suggesting that he’s a terrorist sympathizer.