Former President Donald Trump fired back at former President George W. Bush on Monday in response to comments the latter ex-commander-in-chief made during a 9/11 commemoration speech over the weekend.

Bush raised some eyebrows when he mentioned that international and domestic terrorists and violent extremists, while holding very different worldviews, are "children of the same foul spirit." Both, he suggested, pose significant threats to the United States in their own way. He didn't specify which domestic terror groups he was talking about, but there was some speculation he was alluding to the Jan. 6 Capitol riot. 

Trump seems to be among those who think he was talking about a subsection of his supporters, and lashed out at Bush, whom he blamed for the United States' failures in the Middle East following 9/11. Trump accused Bush of lecturing that domestic terrorists "on the 'right" are "a bigger problem" than "those from foreign countries that hate America," although Bush did not actually say whether he believed one threat was larger than the other or even which end of the political spectrum they're from.