In a letter to the Chief Executive of Twitter on February 6, four Republican senators called on the company to suspend the accounts of the Iranian leadership, including Supreme Leader Ali Khamenei and Foreign Minister Mohammad-Javad Zarif who is a very prolific Twitter user.
In their letter Senators Ted Cruz, Tom Cotton, Marsha Blackburn and Marco Rubio said a Twitter account is a service and provides communications services to the Iranian leadership and as such is not exempt from American sanctions on Iran and designated Iranian officials.
"We therefore call on you to comply with those sanctions by ceasing the provision of services to Khamenei, Zarif, and any other designated Iranian entity," the signatories of the letter who said would provide a copy to President Donald Trump, Secretary Steven Mnuchin and Attorney General William Barr wrote.
In 2014 the Obama administration created exemptions from sanctions for free messaging and social media services to allow Iranians to use these platforms to express their views freely.
At the time all social media was banned in Iran so platforms such as Twitter, Facebook and Instagram were only accessible through VPNs and proxy servers. They still are, except Instagram, but many Iranians manage to use them anyway.
Khamenei's English-language account has had tweets removed for advocating violence in the past. On February 26, 2019, Twitter removed a tweet from his account for appearing to call for the execution of Salman Rushdie, the British novelist whose Satanic Verses brought a death sentence from former Iranian Leader Ayatollah Khomeini and a $3.3 million bounty from an Iranian governmental entity (Bonyad-e 15 Khordad).
In recent months Iranian leaders and the President of the United States and other U.S. officials have exchanged messages on Twitter, with American officials sometimes tweeting in Persian and Iranian officials responding in English.