Former President Donald Trump lashed out Monday at former President George W. Bush, saying his fellow Republican had “a failed and uninspiring presidency” and shouldn’t be “lecturing” Americans about the threat posed by domestic terrorism.

Trump’s comments came two days after Bush, during remarks on the 20th anniversary of the Sept. 11, 2001, terrorist attacks, which occurred during his presidency, warned that there is growing evidence that domestic terrorism could pose as much of a threat to the United States as terrorism originating abroad.

In decrying “violent extremists at home,” Bush appeared to condemn the Jan. 6 insurrection at the U.S. Capitol, when a pro-Trump mob overran the complex in a violent siege that resulted in the deaths of five people.