Short answer: yes

Longer answer: I would argue we’ve already had a few civil wars since the “War Between the States” in the 1860s. Reconstruction was arguably another civil war. The labor rights war of the early twentieth century included federal troops attacking organizing coal miners and federal agents along with private security forces attacking striking workers elsewhere. The violence of the civil rights movement (remember: the president had to call in the national guard to enforce integration) would also qualify as a civil war by some standards.

Listen to the first limited series of the podcast It Could Happen Here for an idea of how a more involved civil war could start. The idea is that there would not be clear battle lines drawn up because our divide now is more urban vs rural, and people in rural areas have opportunities to attack infrastructure that would have significant impacts on urban areas.