Former Secretary of State Hillary Clinton took aim at one of President Donald Trump’s greatest insecurities on Sunday, needling him over the lackluster crowd at his Washington, D.C. military parade this past weekend.

The parade was the spectacle event Trump had long wanted. It also helped sparked the largest mass opposition to him since his inauguration 145 days earlier.

As millions of Americans protested at “No Kings” rallies across the country, onlookers gathered in Washington on the president’s birthday for a muted celebration.