NEW YORK (AP) — The government’s homeland security secretary says the United States is safer now than it was in 2001 against what he calls “another 9/11-style attack.”

But Jeh (jay) Johnson — making the rounds of the Sunday news shows — says the country is “challenged when it comes to the prospects of the lone-wolf actor, the homegrown violent extremists.”

He tells NBC’s “Meet the Press” that requires “a new, whole of government response and public participation and vigilance.”

Hillary Clinton and Donald Trump are attending the Sept. 11 remembrance ceremony in New York.

The presidential candidates greeted supporters on Sunday as they entered the downtown Manhattan memorial. They’re not expected to make public remarks at the event, and both have promised to suspend campaign activities to mark the 15th anniversary of the attacks.

Clinton — a former New York senator — has frequently highlighted her efforts, including in a campaign ad released Friday, to aid those affected by the World Trade Center collapse.

Trump — a New York real estate mogul — has said he donated construction equipment to the recovery effort and gave $100,000 to the memorial after touring it for the first time earlier this year.