Former Secretary of State Hillary Clinton characterized Donald Trump's approach to the world as “dangerously incoherent” on Thursday in a scorching speech about national security and foreign policy in San Diego.

Clinton made the case that a Trump administration would pursue a risky and unpredictable foreign policy agenda, one that would threaten the United States’ relationships with its allies.

“Donald Trump’s ideas aren’t just different, they are dangerously incoherent,” she said. “They’re not even really ideas, just a series of bizarre rants, personal feuds and outright lies. He is not just unprepared, he is temperamentally unfit to hold an office that requires knowledge, stability and immense responsibility.”

The election, Clinton added, presented “a choice between a fearful America that’s less secure and less engaged with the world and a strong, confident America that leads to keep our country safe and our economy growing.”

Clinton had a lot of material to get through. She recited some of Trump’s past statements on foreign policy, provoking laughter from the audience when she noted that he said he understands Russia because he held the Miss Universe pageant there. She also mentioned his past support for increased nuclear proliferation, taking out the families of terrorists and defaulting on the national debt, and mocked his remark that his primary consultant on foreign policy issues is himself, because he has a “very good brain.”

She ridiculed him for saying that climate change is a hoax perpetuated by the Chinese and criticized his statement that he prefers prisoners of war who weren’t captured, like Sen. John McCain (R-Ariz.) was.

“This is not someone who should ever have the nuclear codes, because it’s not hard to imagine Donald Trump leading us into a war just because someone got under his very thin skin,” Clinton said. “We cannot put the security of our children and grandchildren in Donald Trump’s hands, we cannot let him roll the dice with America.”

Clinton noted that Trump has praised leaders like Russian President Vladimir Putin and North Korea’s leader Kim Jong Un, declaring he has a “bizarre fascination with dictators and strongmen.”

“I will leave it to the psychiatrists to explain his affection for tyrants,” she said.

She also criticized Trump for his suggestion that the United States should scale back its involvement in the North Atlantic Treaty Organization.

"If Donald gets his way, they’ll be celebrating in the Kremlin," she said. "We cannot let that happen."

Clinton had to balance the temptation to spend her entire speech mocking Trump with her desire to appear presidential, which is perhaps why she spoke in front of a backdrop of American flags in San Diego, a city that has a strong connection to the military.

She already has an edge against Trump when it comes to national security. A NBC News/Wall Street Journal poll found that 56 percent of Americans believe she would be better at handling foreign policy, compared to 29 percent who thought Trump would be better. She also led Trump by 10 points on the question of who would be a better commander-in-chief.

She noted that her tenure as secretary of state gives her the type of foreign policy experience Trump lacks, mentioning her work to advance agreements to fight climate change, a ceasefire between Israel and Hamas, a nuclear weapons reduction deal with Russia and sanctions against Iran. She also pointed out that she was in the Situation Room with President Barack Obama debating whether to initiate the raid that killed Osama bin Laden.

“I’m not new to this work, and I’m proud to run on my record, because I think the choice before the American people in this election is clear,” she said. “Making Donald Trump commander-in-chief would be a historic mistake.”

Trump has attempted to walk back some of his past statements while simultaneously arguing that Clinton is misrepresenting them. On Wednesday, for instance, he claimed that he had never said Japan should have nuclear weapons, though he said exactly that, arguing that Japan would be better off if it had nuclear weapons to defend itself against North Korea.

The reality television star and presumptive GOP nominee frequently calls Clinton's judgment into question by noting that she supported the United States’ invasion of Iraq and intervention in Libya, even though he supported both of those endeavors as well. His claim that he was prophetically opposed to the Iraq War “from the very beginning” has been thoroughly debunked by numerous news and fact-checking outlets.

Trump didn't respond substantively to Clinton's remarks, but tweeted that she didn't look presidential.

Bad performance by Crooked Hillary Clinton! Reading poorly from the telepromter! She doesn't even look presidential! — Donald J. Trump (@realDonaldTrump) June 2, 2016

While Clinton’s speech made it seem like the general election has already begun, she is spending the next five days campaigning in California, where Sen. Bernie Sanders (I-Vt.) threatens to embarrass her in what polling suggests is a tight race ahead of the state’s June 7 presidential primary.

Sanders said in a statement Thursday afternoon that while he agreed with Clinton that Trump's foreign policy ideas "are incredibly reckless and irresponsible," he wanted to remind voters that Clinton voted for the war in Iraq, "the worst foreign policy blunder in modern American history," and supported regime change in Libya, "without thinking through the consequences."

"We need a foreign policy based on building coalitions and making certain that the brave American men and women in our military do not get bogged down in perpetual warfare in the Middle East," Sanders said. "That's what I will fight for as president."

Clinton is only about 70 delegates away from reaching the 2,383 she needs to secure the Democratic nomination, if one counts the pledged and super delegates already supporting her campaign.

﻿This story has been updated with a statement from Sen. Bernie Sanders.

Editor’s note: Donald Trump regularly incites political violence and is a serial liar, rampant xenophobe, racist, misogynist and birther who has repeatedly pledged to ban all Muslims — 1.6 billion members of an entire religion — from entering the U.S.