Donald Trump unveiled his plan Wednesday for boosting defense spending and rebuilding the military, while calling for a new strategy to defeat the Islamic State, as part of a renewed focus by his campaign on national security.

The Republican nominee also used the speech in Philadelphia to blast Hillary Clinton’s foreign policy experience as secretary of state, which she has used as a central pillar of her campaign.

Trump called Clinton “trigger-happy and very unstable” and pointed to the unrest in Libya, Syria and Iraq.

“This is Hillary Clinton’s foreign policy legacy -- failure and death,” he said, before saying the recently released notes from the FBI probe into her private email server show that she is “totally unfit to be our commander-in-chief.”

For his own military policy, he outlined a number of proposals, including:

Asking military generals to present a plan within 30 days to defeat and destroy ISIS, immediately after taking office

Asking Congress to eliminate the defense sequester

Building an active Army of about 540,000

Building a Marine Corps based on 36 battalions

Building a Navy nearing 350 surface ships and submarines

Building an Air Force of at least 1,200 fighter aircraft

A new "state-of-the-art" missile defense system

Trump said that the increase in spending would come from cuts in waste and streamlining bureaucracy.

Trump's address came hours before his national security acumen is tested at a "commander in chief" forum on NBC.

The appearances mark an intense, two-day focus on national security by Trump, who has offered tough rhetoric on America's challenges abroad but few details.

"I'm going to make our military so big, so powerful, so strong, that nobody -- absolutely nobody -- is gonna to mess with us," Trump says in a 23-second video posted on his campaign website.

The United States already spends more than $600 billion a year on the military.

Trump's description of Clinton as “trigger happy” comes after Clinton has tried to paint the billionaire businessman as erratic, making the case that his disposition would be a major liability on the world stage.

"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."

Trump has pushed back on that characterization.

"I think my single greatest asset, of any assets I have, is my temperament," Trump declared in North Carolina on Tuesday.

While Clinton and Trump will be featured at the Wednesday night forum, they will appear at separate times and will not face each other on stage. The forum could serve as a warm-up to their highly anticipated first presidential debate, scheduled for Sept. 26 in New York.

Trump will deliver another speech Wednesday evening, at the convention of New York's Conservative Party, that's also expected to focus on national security.

Meanwhile, Clinton on Wednesday rolled out a list of endorsements from retired generals and admirals.

Clinton's campaign announced that she now has 95 retired generals and admirals backing her candidacy. That's more than the list of 88 retired military leaders that Trump's campaign announced on Tuesday.

Among Clinton's new supporters is retired General Lloyd Newton who served in the Air Force.

Fox News’ Christopher Snyder and The Associated Press contributed to this report.