The Islamic Republic of Iran imposed sanctions on 51 more Americans in retaliation for the killing of General Qaseem Soleimani in January of 2020. These new sanctions are against Americans suspected by Iran of being involved in the drone strike that killed the General. These names are added to a list that includes former President Donald Trump and other senior officials who were sanctioned last year immediately following the strike.
While it's expected that these sanctions will have no effect, as the parties sanctioned have no holdings in Iran that the government there can freeze or seize, it is a symbolic attempt to keep the memory of the event alive.
This occurs amid the quiet backdrop, not mentioned in the White House's press statements, of meeting with the P5+1 (China, Germany, France, Russia, the United Kingdom, and the United States) in Vienna to work toward restoring the 2015 nuclear deal with Iran that Trump walked away from in May of 2018. Trump stated at the time that the deal was fatally flawed. Reports from those talks indicate that Iran is taking a hardline against letting UN inspectors in to see their nuclear program.
In January of 2020, just weeks before leaving office, Trump ordered a drone strike on Soleimani as he arrived in Iraq.
The White House steadfastly repeated its determination to protect Americans and American assets from physical attack by Iran. "We are united in the defense of our people. We will work with our allies and partners to deter and respond to any attacks carried out by Iran," a White House statement read. "Should Iran attack any of our nationals, including any of the 51 people named yesterday, it will face severe consequences."
Talks continue in Vienna, but progress is not expected.
https://www.whitehouse.gov/briefing-room/statements-releases/2022/01/09/statement-by-national-security-advisor-jake-sullivan-on-iranian-threats-and-provocations-against-american-citizens/