CNN
In the speech, Clinton lobbed Trump-esque insults at the presumptive Republican nominee in an apparent effort to match his headline-grabbing style.
"Donald Trump's ideas aren't just different, they're dangerously incoherent," Clinton said at the beginning of her speech, calling his policy declarations "a series of bizarre rants, personal feuds, and outright lies."
She set out to cast herself as the more qualified candidate, questioning Trump's foreign-policy credentials.
"He says he has foreign-policy experience because he ran the Miss Universe pageant in Russia," Clinton said.
Clinton also hit Trump over his suggestion that South Korea and Japan could be able to obtain nuclear weapons to defend themselves.
"I wonder if he even realizes he's talking about nuclear war," she said.
She also questioned his temperament and mocked his bragging pronouncements about his capabilities.
"It's not hard to imagine Donald Trump leading us into a war just because somebody got under his very thin skin," she said. "He says he doesn't have to listen to our generals or ambassadors, because he has - quote - 'a very good brain.'"
Later, she criticized Trump's favorable statements about strongmen like Russian President Vladimir Putin.
"I will leave it to the psychiatrist to explain his affection for tyrants," Clinton said. "I just wonder how anyone could be so wrong about who America's real friends are."
Trump was responding to Clinton's speech as it was ongoing. He tweeted:
Crooked Hillary no longer has credibility - too much failure in office. People will not allow another four years of incompetence!
- Donald J. Trump (@realDonaldTrump) June 2, 2016
Bad performance by Crooked Hillary Clinton! Reading poorly from the telepromter! She doesn't even look presidential!
- Donald J. Trump (@realDonaldTrump) June 2, 2016