Donald Trump has said he will expand all areas of the US military if he wins the presidency in November.
The Republican candidate said he wanted more soldiers and marines, more planes and more boats.
He also said he would come up with a plan to destroy Islamic State (IS) in his first 30 days in the White House.
He said his plan would be paid for by cutting government waste, collecting uncollected taxes and slimming down the federal workforce.
In a speech in Philadelphia, he also said he wanted "peace through strength" and for all America's Nato allies to meet their obligations to spend 2% of national income on defence.
"I am proposing a new foreign policy focused on advancing America's core national interests, promoting regional stability, and producing an easing of tensions in the world. This will require rethinking the failed policies," he said.
He added: "Our adversaries are chomping at the bit."
Earlier this week, Mr Trump was endorsed by 88 former military leaders in an open letter.
The group of retired generals and admirals declared the Republican nominee "has the temperament to be commander-in-chief".
Mr Trump has highlighted veterans' issues during his campaign.
Both Mr Trump and Mrs Clinton will take part back-to-back in a national security forum on Wednesday.
The forum, to be hosted by the Iraq and Afghanistan Veterans of America, will include questions from an audience of military service members.
Also on Tuesday, Mrs Clinton released a campaign ad featuring veterans who are critical of Mr Trump.
Her ad includes a clip of Mr Trump from July 2015 casting doubt on leading Republican John McCain's war hero credentials.
Arizona Senator McCain was tortured for more than five years as a prisoner of the North Vietnamese.
Despite making support for the military a signature issue in his campaign, Mr Trump has at various times drawn criticism from military members.
Most notably, he was involved in a recent spat with family members of a Muslim-American soldier killed during the Iraq War.
Mr Trump, who has not served in the military, also created a stir last month when he accepted a veteran's gift of a Purple Heart.
"I always wanted to get the Purple Heart," he said of the medal, which is awarded to soldiers wounded in war. "This was much easier."