Former President George W. Bush drew a parallel between foreign and domestic extremists in his speech to mark the 20th anniversary of the 9/11 attacks from Shanksville, Pennsylvania, on Saturday. He condemned both equally.

We have seen growing evidence that the dangers to our country can come not only across borders, but from violence that gathers within, Bush said from the field where Flight 93 crashed on Sept. 11, 2001, amid a struggle between terrorists and passengers.

There is little cultural overlap between violent extremists abroad and violent extremists at home, Bush said, but in their disdain for pluralism, in their disregard for human life, in their determination to defile national symbols, they are children of the same foul spirit, and it is our continuing duty to confront them.

While Bush did not explicitly touch on the Jan. 6 Capitol riots, his speech inevitably invoked the domestic attack on the seat of American political power that was spurred on by one of his successors, President Donald Trump .

Domestic extremism proliferated in the years after the 9/11 attacks as much of Americas resources as directed under the Bush administration and the subsequent Obama administration were focused instead on the threat of international terrorism. The FBI now considers domestic extremism a top threat to national security .