U.S. presidential candidates Donald Trump and Hillary Clinton put their contrasting plans on the economy and America's role overseas in front of potential voters Monday night as they squared off in the first of three head-to-head debates.
Trump repeated his assertion that Clinton lacks the stamina to be president, and said her policies have led to a range of problems facing the country, including the threat posed by the Islamic State group.
Clinton portrayed Trump's economic plans as favoring the rich over the middle class and suggested he does not want to make his tax returns public because he is not as rich as he says or is hiding something that would be a conflict of interest if he were elected.
WATCH: Clinton blasts Trump on 'Trumped up trickle down economy'
The debate was the first of three they will have before Americans vote on November 8.
Clinton touted her experience traveling to more than 100 countries and negotiating peace deals and cease-fires while secretary of state during President Barack Obama's first term.
Trump responded that while she has experience, it is "bad experience." He sharply criticized the nuclear deal the United States and five other powers struck with Iran to limit the country's nuclear program, while Clinton cited it as an example of effective diplomacy that cut off Iran's path to a nuclear bomb.
The two candidates did agree that nuclear weapons are the biggest threat facing the world, and that anybody who appears on a terror watch list should not be allowed to buy a gun.
Clinton called for criminal justice reforms to "restore trust between communities and police" and to make sure that officers only use force when necessary.
Trump emphasized the need to "bring back law and order" and promoted his plan to bring back controversial "stop and frisk" policing.
WATCH: Trump on 'stop and frisk' policing
"We have a situation where we have our inner cities, African-Americans, Hispanics, are living in hell because it's so dangerous. You walk down the street, you get shot," Trump said.
Clinton rejected that view of black communities, calling it "dire."
"There's a lot that we should be proud of and that we should be supporting and lifting up."
Both candidates also noted the threat posed by cyber attacks from abroad, saying the U.S. needs to do more to fight back.
On the war in Iraq, Trump strongly asserted that he never supported the war, despite interviews he gave at the time suggesting he did. He criticized the Obama administration's handling of withdrawing U.S. forces, saying at least 10,000 troops should have stayed behind and that coupled with "taking the oil" would have prevented the rise of the Islamic State group.
Clinton pointed to the Iraqi government's unwillingness to agree to a Status of Forces Agreement that would give legal protections to American troops as a key in the decision to pull out.
The next debate will be October 9. Trump's running mate Mike Pence and Clinton's running mate Tim Kaine will have their only debate on October 4.
WATCH: Political correspondent Jim Malone sums up the debate