GREENVILLE, N.C. — Donald Trump said Tuesday night that Hillary Clinton’s handling of private emails disqualifies her to serve as president. His own temperament, Trump said, was his “single greatest asset” and not the national security danger that Clinton alleges.

Trump’s charge, delivered to a packed crowd in swing state North Carolina, marked a pointed escalation of the Republican White House hopeful’s case against his Democratic challenger as both court military families in key Southern battlegrounds. Clinton, meanwhile, accused Trump of insulting America’s veterans and pressing dangerous military plans around the globe.

Clinton, addressing supporters in Florida, warned that Trump would lead the nation back to war in the Middle East. And to military vets and their families, she pointed anew to his summertime dust-up with the Muslim parents of a slain American soldier.

“His whole campaign has been one long insult to all those who have worn the uniform,” the Democratic nominee said at the University of South Florida in Tampa.

Trump, trying to emphasize his military support, released a letter from 88 retired generals and admirals citing an urgent need for a “course correction” in America’s national security policy. It was aimed at rebutting Clinton’s arguments that she would be best positioned to lead the military and reassuring Republicans who have openly worried that his provocative statements might undermine U.S. alliances.

“We believe that such a change can only be made by someone who has not been deeply involved with, and substantially responsible for, the hollowing out of our military and the burgeoning threats facing our country around the world,” the military leaders wrote. “For this reason, we support Donald Trump’s candidacy to be our next commander in chief.”

Trump promoted the letter as he campaigned in Virginia and North Carolina on Tuesday, suggesting that he would rely on the generals to make up for his own lack of national security inexperience to take on the Islamic State group. He vowed to give military leaders a “simple instruction” soon after taking office: “They will have 30 days to submit to the Oval Office a plan for soundly and quickly defeating ISIS.”

Clinton pushed back, saying Trump has lagged in securing key military supporters compared to past Republican nominees including John McCain and Mitt Romney. She pointed to her endorsements from retired Marine Gen. John Allen, who blasted Trump at the Democratic National Committee, and former CIA deputy director Mike Morell.

“They know they can count on me to be the kind of commander in chief who will protect our country and our troops, and they know they cannot count on Donald Trump,” Clinton said en route to Florida. “They view him as a danger and a risk.”

The conflicting messages came as the candidates prepared to appear at an MSNBC forum Wednesday night on national security. While they will appear separately and not be on stage at the same time, it could serve as a warm-up to their highly-anticipated first presidential debate on Sep. 26 in New York.

Meanwhile, Clinton’s campaign released a new television ad entitled “Sacrifice,” showing military veterans watching some of the New York businessman’s more provocative statements.

The spot includes clips of Trump claiming to know more about the Islamic State group than military generals, and his criticism of McCain, the Republican senator from Arizona and a former prisoner of war. The ad, which features former Georgia Sen. Max Cleland, a triple-amputee who served in Vietnam, also keys on Trump’s assertion that he has sacrificed a lot compared to families who have lost loved ones in conflict.

“Our veterans deserve better,” reads a line at the end of the ad, which is airing in Ohio, Florida, Iowa, Nevada and Pennsylvania.

Separately, Trump continued to face questions about his immigration policy a day after refusing to rule out a pathway to legal status for immigrants in the country illegally. He focused on his proposed border wall plan in a Tuesday interview with ABC’s “Good Morning America.”

Last week in Phoenix, he told a raucous crowd of supporters that there was “one way only” for immigrants here illegally to become legal — to return home and get in line for official re-admittance.