Tehran, Iran — Hundreds of thousands of people across Iran took to the streets Monday to mark the 40th anniversary of the country's Islamic Revolution. Speaking in the capital Tehran, President Hassan Rouhani told a huge crowd Iran didn't need to ask the world's permission to develop missiles, and it would continue to build up its military power despite U.S. sanctions.

CBS News correspondent Elizabeth Palmer was in the crowd and said despite lousy weather, there was a festive atmosphere at the anniversary parade.

Some of the people in the crowd were old enough to have actually participated in the revolution, but for the younger ones, the Islamic Republic that followed is the only country they've ever known. That means all they've ever known is a relationship with the U.S. that ranges from hostile, to downright toxic.

An Iranian boy holds up a sign reading "Down with USA" as he assembles with others during a ceremony celebrating the 40th anniversary of Islamic Revolution by the capital Tehran's Azadi (Freedom) tower in the square of the same name on Feb. 11, 2019. Getty

We're at an especially low point right now; the Trump administration has imposed the harshest sanctions on Iran to date, which they say are meant to weaken the ruling regime.

Chants of the familiar "Death to America" refrain echoed through the streets of Tehran on Monday in response. This year, Iran's supreme leader Ayatollah Ali Khamenei stressed just before the anniversary, however, that the chant was not aimed at the American people, but their leaders.

Iran "will not stop saying 'Death to America' as long as the U.S. acts malicious" toward Iran," Khamenei said.

Rouhani spoke to the crowd in Tehran on Monday for 45 minutes. He lambasted what he called U.S. and Israeli efforts to "bring down" Iran through sanctions.

"The presence of people in this celebration means that plots by the enemies... have been defused," he said. "They will not achieve their ill-omened aims."

While the Iranian economy has without doubt felt the pressure of the ramped-up U.S. sanctions, Palmer said there are no signs yet that the regime is losing its grip.

The crowd in Tehran was full of ardent supporters. Palmer asked a man with his son why he came out into the streets on Monday.

"Because the people of Iran. They believe that the revolution and also the government belongs to them. They, 40 years ago, they came to the street," he said. He was in the streets himself four decades ago.

"I was six years old, and now I brought my son here to actually hand over the revolution to them after 40 years," he said.

The Revolution in 1979 drew millions into the streets — excited by the promise of a better, fairer Iran. And there were successes, like good universal education. But there were huge disappointments, too.

Asked what he believed the main failure of the revolution has been, the man conceded that the Islamic Republic's leaders might not always be acting in the Iranian people's best interests.

"Financial corruption is everywhere," he said. "Economic corruption. Lots of thieves among them, who just steal millions of dollars, even billions of dollars."

One of the revellers even conceded to Palmer that given the opportunity, he would leave Iran to join the thousands of other professionals who have fled the restrictive nation to build lives elsewhere.

But the young man standing next to them in the crowd didn't like what he was hearing. For him, criticizing Iran in public to foreigners was simply unacceptable.

The man grew aggravated with Palmer's line of questioning, getting in her face and demanding to know why she was "asking some questions that all, all of them are against Iran?" He angrily suggested that Palmer leave the country.

But Palmer, who has travelled to the Islamic Republic for years, said that kind of hostility is rare in the country. Even the U.S. flag burnings and the Death to America chants are more tired ritual than real aggression.

The truth is that millions of Iranians are fed up, with their own government and with America's threats. They've accepted the Revolution hasn't delivered utopia, all they want now is stability and a decent life.

But that is life for the millions of Iranians who are not leading their government. Whenever the U.S. cracks down with sanctions and tough talk, the Iranian regime steps up and flexes some provocative muscle.

CBS News correspondent Elizabeth Palmer, left, speaks to an Iranian man who joined thousands of others on the streets of Tehran, Feb. 11, 2019, for festivities marking the 40th anniversary of the Islamic Revolution which brought the current regime to power. cbs

Palmer heard President Rouhani tell the crowd that Iran would continue to expand its military power, and earlier this month the Islamic Republic tested a brand new cruise missile.

The deputy head of Iran's elite Revolutionary Guards, Yadollah Javani, was quoted on Monday by state news agency IRNA as saying, "the United States does not have the courage to shoot a single bullet at us despite all its defensive and military assets. But if they attack us, we will raze Tel Aviv and Haifa to the ground."

Iran often directs its bellicose rhetoric at both Israel and the U.S. Many of Iran's rockets are capable of reaching Israel. Under the previous president, the regime called for the Jewish state to be "wiped off the map."

An anchor on Iranian state TV quipped on Monday about how he expected President Trump's National Security Adviser John Bolton to be angry as he watched the images from Terhan this week, given that he suggested just last year that the Iranian regime was doomed to crumble in months.

According to The Associated Press, Bolton told a meeting of Iranian exiles in 2018 that, "before 2019, we here ... will celebrate in Iran."