Iran’s government displayed a ballistic missile while crowds chanted “Down with the U.S.” and burned an American flag as the country marked the anniversary of the 1979 U.S. embassy takeover and hostage crisis on Saturday.

Thousands of people gathered in front of the former embassy site in Tehran to commemorate one of the pivotal events of the Islamic Revolution.

In an apparent show of force, the gathering included a surface-to-surface Sejji missile with a range of 1,200 miles. It was the first time Iran had displayed a missile at the annual event and comes a month after President Trump refused to re-certify Iran’s compliance with its 2015 nuclear deal with world powers.

Iran’s leaders say they are proud of its missile program.

“That America thinks Iran is going to put aside its military power is a childish dream,” said Brigadier General Hossein Salami, deputy head of its elite Revolutionary Guards which oversees the missile development, Reuters reported, citing the Iranian news agency Tasnim.

The Fars news agency posted pictures of demonstrators burning an effigy of Trump and holding up signs saying “Death to America,” Reuters reported.

Hundreds of Iranian militant students stormed the U.S. Embassy after the overthrow of the U.S.-backed Shah Mohammad Reza Pahlavi. They took 52 Americans hostage for 444 days after Washington refused to hand over the shah, who was in the U.S.

The siege led to a break in diplomatic relations that remains severed to this day.

President Trump refused to re-certify the 2015 landmark nuclear deal between Iran and world powers in October and the U.S. has imposed more sanctions on Iran over its ballistic missile program.

The U.S. Congress must now make a decision regarding the 2015 nuclear deal, in which Iran agreed to limit its enrichment of uranium in exchange for the lifting of economic sanctions.

Ali Shamkhani, secretary of the country's Supreme National Security Council, addressed the crowd, saying Iran will make any sanctions imposed by the U.S. "ineffective" even as the U.S. targets Iran's economic, nuclear and defensive power.

Shamkhani, alluding to Trump's threats against North Korea, said even U.S. allies know that Trump "has no power to realize his bluffs, against Iran, too." He called the U.S. the "eternal enemy" of Iran.

The former embassy in Tehran is now a cultural center while standing as a symbol of a U.S. defeat for many Iranians. Many Iranians call it the "den of spies."

The Associated Press contributed to this report.