President Donald Trump has made national security a centerpiece of his agenda, justifying policies ranging from a travel ban to close relations with Russia. But the United States is now more vulnerable to attack than it was before Trump took office, according to the man who served as George W. Bush’s crisis manager on 9/11. “In terms of a major terrorist attack in the United States or on U.S. facilities, I think we’re significantly less ready than we were on January 19,” said Richard Clarke, who served on the National Security Council in the George H.W. Bush, Bill Clinton, and George W. Bush administrations. “I think our readiness is extremely low and dangerously low. Certainly [government] agencies at a professional level will respond [to an attack], but having a coordinated interagency response is unlikely given the current cast of characters [in the administration] and their experience.” Clarke’s conclusion is based in part on the upheaval on the National Security Council, an organization created in 1947 within the White House to coordinate national-security policymaking across the federal government. His assessment is also based on the background of the council’s leaders; Flynn’s deputy, K. T. McFarland, was previously a Fox News analyst and last worked in government as a public-affairs official in the Reagan administration, over thirty years ago. Tom Bossert, Trump’s homeland-security adviser, has experience responding to natural disasters, Clarke pointed out, and military veterans, like H. R. McMaster, who was announced yesterday as Michel Flynn’s replacement, had a wealth of combat experience — but that’s different than ensuring that a hulking government bureaucracy reacts swiftly and effectively to an incident like a terrorist attack. “I don’t know that there’s a single person [on Trump’s National Security Council] who’s ever had a senior position managing a national-security crisis out of Washington,” Clarke said.