Iran is commemorating the 40th anniversary of the 1979 student takeover of the U.S. Embassy in Tehran and the subsequent 444-day hostage crisis.
State media report that government-sponsored rallies have begun in nearly 1,000 cities and towns across the country.
In Tehran, state television showed crowds packing the streets around the former embassy dubbed the "den of spies" after the 1979 Islamic Revolution. News agencies posted images of protesters setting the U.S. flag on fire.
Participants were chanting slogans against the United States, including "Death to America," and Israel, according to the hard-line Fars news agency.
"Our fight with America is over our independence, over not submitting to bullying, over values, beliefs, and our religion," army chief Major General Abdolrahim Musavi said in a speech at the rally.
The United States "will continue its hostilities...unless it is crushed," Musavi said in remarks carried by state-run television.
The anniversary this year comes amid heightened tensions between Iran and the United States following a decision by U.S. President Donald Trump to withdraw Washington from the 2015 nuclear deal between Tehran and world powers and reimpose crippling sanctions on Iran.
On November 4, 1979, militant students stormed the U.S. Embassy in Tehran, taking 52 Americans hostage for 444 days after Washington refused to hand over Iran's toppled shah, Mohammad Reza Pahlavi, for trial in Iran.
PHOTO GALLERY: Looking Back At The U.S.-Iran Hostage Crisis (click to enlarge)
The two countries have had no diplomatic relations since then.
Iranian Supreme Leader Ayatollah Ali Khamenei on November 3 renewed a ban on talks with the United States, describing the two countries as implacable foes.
"Those who believe that negotiations with the enemy will solve our problems are 100 percent wrong," Khamenei was quoted as saying by domestic media.