As anti-government protesters took to the streets in Tehran against Iranian Supreme Leader Ayatollah Ali Khamenei, President Donald Trump tweeted in support and called for international monitors.
"The government of Iran must allow human rights groups to monitor and report facts from the ground on the ongoing protests by the Iranian people," Trump tweeted in English and Farsi. "There can not be another massacre of peaceful protesters, nor an internet shutdown. The world is watching."
Trump was referencing the Iranian government's crackdown on anti-government protests over a spike in gas prices last November. The government quashed protests by arresting, injuring and killing protesters and shutting down the country's internet.
On Friday, the Iranian government accepted blame for the downing of a Ukrainian airliner Wednesday, sparking protests against the Iranian government's handling of the incident.
The United Kingdom Ambassador to Iran was arrested and briefly detained by Iranian authorities after attending Saturday's protest. British Foreign Minister Dominic Raab slammed the arrest as a "flagrant violation of international law."
In a tweet, State Department spokesperson Morgan Ortagus called on the Iranian government to apologize to the British government and to "respect the rights of all diplomats."
The Ukrainian jet was shot down by the Iranian military, which had mistaken it for a cruise missile, killing all 176 people aboard. The government had insisted a missile had not caused the plane's crash. But in a statement on Friday Eastern Standard Time, the Iranian military said the plane was mistaken for a “hostile target” after it turned toward a “sensitive military center” of the Revolutionary Guard. The statement was carried by Iranian state media on Saturday morning local time.
The plane's downing occurred shortly after Iranian missiles struck U.S. bases in Iraq in retaliation for the killing of top Iranian General Qasem Soleimani in an airstrike ordered by Trump.
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The tensions between the two countries, however, did not reach any further levels of military escalation. On Thursday, Trump announced further sanctions on Iran, saying Iran "appears to be standing down."
Trump also tweeted a message in both English and Farsi expressing support for the people of Iran.
"We are following your protests closely, and are inspired by your courage," he wrote.