During the debate on Wednesday night, Pence tried to portray President Donald Trump's policies on Iran and other issues as a great success, while Harris denounced the president's approach as erratic, Middle East Eye reported.
When discussing Washington's relationship with its allies, Harris berated the US administration for withdrawing from the Iran nuclear deal and accused Trump of failing to live up to America's commitments.
She said nixing the multilateral pact harmed the United States' security.
"We were in the Iran nuclear deal with friends, with allies around the country," Harris said. "And because of Donald Trump's unilateral approach to foreign policy, coupled with his isolationism, he pulled us out and has made America less safe."
The agreement, known as the Joint Comprehensive Plan of Action (JCPOA), was signed between Iran and the world powers in 2015.
Trump left the pact in May 2018 and has piled sanctions on various Iranian industries and individuals ever since. In turn, Iran has reduced some commitments based on the frameworks of the pact.
The agreement was signed when Joe Biden was serving as Barack Obama's vice president in 2015. Biden has vowed to rejoin the JCPOA if elected as the president.
"The thing that has always been part of the strength of our nation - in addition to our great military - has been that we keep our word, but Donald Trump doesn't understand that because he doesn't understand what it means to be honest," Harris said on the debate stage.
Elsewhere, Pence defended the US terrorist act of the assassinating top Iranian general Qassem Soleimani in January, claiming that Americans are safer because of Trump.
He said but Biden and Harris actually criticized the decision to assassinate General Soleimani.
Both Biden and his running mate had indeed questioned Trump's decision at the time, with many Democrats sounding the alarm against a possible all-out war with Iran and criticizing the president for lacking a sound strategy after leaving the nuclear deal.
Harris said, "It is essential that Congress take its constitutional responsibility seriously and work to de-escalate the situation."
MR/PR