The speech, which will kick off five days of campaigning ahead of California's June 7 primary, is set to cast Trump as a foreign policy lightweight and security risk, according to aides, and highlight Clinton's experience on the international stage. The speech is in San Diego, in part, because of the many military personnel in the city.
Clinton plans to "make clear the threat that Donald Trump would pose to our national security and to put forth her own vision for keeping America safe at home and leading in the world," a campaign press release said about the speech.
"Clinton will rebuke the fear, bigotry and misplaced defeatism that Trump has been selling to the American people," said one senior aide. "She will make the affirmative case for the exceptional role America has played and must continue to play in order to keep our country safe and our economy growing."
Since Trump became the presumptive Republican nominee, Clinton has directly challenged his ability to handle foreign policy issues and has taken to labeling him a "loose cannon" who will make it more difficult for the United States to operate on the global arena.
"I have to tell you, I think that Donald Trump has disqualified himself completely," Clinton said in regard to foreign policy on Wednesday in New Jersey. "He has attacked out closest ally, said we should pull out of NATO, he has praised the dictator of North Korea, he has advocated more countries get nuclear weapons ... he has advocated a return to torture and he has said he wants to ban all Muslims from entering the United States."
She added, "This is not just divisive rhetoric, my friends. This is dangerous. It is dangerous. It will make us more vulnerable."
Clinton's campaign feels, because of her experience as a senator and secretary of state, Clinton will be able to use her experience to effectively hit Trump on national security.
Trump, on the other hand, has questioned her judgment about interventions in Iraq and Libya -- two conflicts Clinton backed -- but has left out the fact that he previously supported them, too.
"She doesn't have the temperament to be president. She's got bad judgment. She's got horribly bad judgment," Trump said last week
. "If you look at the war in Iraq, if you look at what she did with Libya, which was a total catastrophe."
Clinton, then a senator, voted in 2002 to authorize the use of military force in Iraq. And as secretary of state in 2011, she forcefully argued in favor of military intervention to overthrow Libyan dictator Moammar Gadhafi.
Clinton's speech on Thursday will kick off five days of campaigning ahead of the California primary, where Clinton is in a close race with Vermont Sen. Bernie Sanders.