 -- The United States has requested a U.N. Security Council meeting on Friday afternoon to discuss "the troubling and dangerous situation" in Iran, the U.S. Mission to the U.N. announced Thursday night.

At least 21 people have been killed and hundreds, if not more, arrested over the past week in protests and unrest, which began amid grievances over economic woes. It has since expanded into a nationwide show of dissent against the country's leadership. Iran's interior minister said up to 42,000 people took part in the protests.

"Tomorrow the UN Security Council will discuss the troubling and dangerous situation in Iran," U.S. ambassador to the U.N. Nikki Haley said in a statement Thursday. "The world has witnessed the horrors that have taken place in Syria, that began with a murderous regime denying its people’s right to peacefully protest. We must not let that happen in Iran."

Haley continued, "This is a matter of fundamental human rights for the Iranian people, but it is also a matter of international peace and security. It will be telling if any country tries to deny the Security Council from even having this discussion, just as the Iranian regime tries to deny its own people the ability to have their voices heard."

There have been questions, however, as to where the protest movement will go from here. Already on Thursday, turnout was notably smaller than previous days. On Wednesday tens of thousands of Iranians participated in counter-demonstrations backing the government, which has claimed that the U.S. and its other "enemies" are fueling the protests.

In a statement shown on state television Tuesday, Supreme Leader Ayatollah Ali Khamenei said, "In the events of recent days, the enemies have united and are using all their means, money, weapons, policies and security services to create problems for the Islamic regime ... The enemy is always looking for an opportunity and any crevice to infiltrate and strike the Iranian nation."

President Trump has doubled down in his public support for the protests, breaking from the more cautious approach President Obama took when massive protests broke out in Iran in 2009.

"Such respect for the people of Iran as they try to take back their corrupt government. You will see great support from the United States at the appropriate time!" Trump tweeted on Wednesday.