Until recently, Iran has been the distant third among disinformation superpowers, with Russia and China ahead in spreading false claims attacking the U.S. and sowing divisions in the country. With the election of Donald Trump, Tehran has accelerated its efforts, putting disinformation just behind assassination as a malign state strategy.  Consider how the mullahs responded on Nov. 6, the day after Trump was elected: They used social media to reissue their threat to kill Trump and launched a disinformation campaign falsely claiming that Trump views Iran as “a powerful country.”   Hours after Trump was declared the victor, the social media account on Telegram used by Iran's Islamic Revolutionary Guard Corps posted a video showing Trump in a sniper’s crosshairs, ending with the crack of a gunshot and Trump spitting up blood.  The video voiceover is a speech from 2018 by the terrorist mastermind who ran that paramilitary organization's Quds-Force, Qassem Soleimani, who was killed by U.S. forces in 2020 on Trump’s orders. The audio says, “Oh Mr. Trump, the gambler! I tell you that the Quds Force is your opponent!” The video ends with the warning that “unfinished work will be finished soon!”   The Iranian death threat seems real. Days after the election, the Department of Justice filed criminal complaints against kill-for-pay assassins allegedly tasked by the Islamic Revolutionary Guard Corps in September to murder Trump.  This election-day-after assassination video was posted on the social media platform Telegram by Bisimchi Media. This is significant because Bisimchi Media reports directly to top mullah Ali Khamenei as part of the Islamic Revolutionary Guard Corps, which conducts Iran’s terrorism around the world, separate from the country’s conventional armed forces.   The Islamic Revolutionary Guard Corps then deployed disinformation alongside its Trump death threat and plot. Later the same day, Farsi-speaking NewsGuard analyst McKenzie Sadeghi spotted another Trump-related post on Bisimchi Media’s Telegram account. This one claimed that Trump praised Iran and its mullahs in his 2015 book “Crippled America.” The social media channel posted a screenshot from the book with a passage purporting to show that Trump wrote, “Iran is a powerful nation as long as religious hardliners govern it.”   This is not what Trump wrote. This section of “Crippled America” says the opposite. Trump wrote, “Iran was a powerful nation until religious fanatics took over. As long as those people remain in power, Iran will be our enemy and a threat to Israel’s existence.” The fake quote from the book, however, was spread widely by Iran's Fars news agency and on social media platforms, including X. This is not the first time Iran has used the internet to make false claims for its domestic audience and to exert malign foreign influence on Americans and our allies. In August, the U.S. intelligence community issued a warning that Iran had an “increased intent to exploit our online platforms in support of their objectives,” especially in the runup to the election.   NewsGuard analysts have identified 19 websites secretly operated by Iran but posing as independent news sites in the West. These included Savannah Time, which described itself as a conservative site, Nio Thinker, which claimed to be liberal, and Afro Majority, which claimed to be a legitimate publication aimed at Black readers. They had in common that they spread pro-Iran, anti-American claims. Nio Thinker, for example, called Trump an “opioid-pilled elephant in the MAGA china shop.”   This Iran network of fake news sites uses AI to spread its disinformation. Its Afro Majority website was caught using AI to craft a divisive narrative, with the prompt for a story: “Delve into the pivotal role of the Black Lives Matter movement in shaping the discourse and dynamics of the upcoming 2024 presidential election. Explore how [Black Lives Matter’s] mobilization efforts, advocacy campaigns, and challenges intersect to influence the pursuit of racial justice and social change in the United States.”  Several of Iran’s 19 fake news sites also used AI to write political commentaries, then falsely credit them to leading figures in the U.S. These include commentaries falsely attributed to WNBA star Brittney Griner, attorney Alan Dershowitz and former Illinois Rep. Adam Kinzinger (R-Ill.).  In the weeks before the U.S. election, NewsGuard analysts identified 90 significant provably false claims related to the U.S. election. Of these, we found that 35 came from or were spread by hostile foreign governments, including Russia and Iran. This 39 percent of false election claims is a measure of how much effort our adversaries put into undermining U.S. information sources and claims.   Securing Americans from hostile government false claims takes more than identifying and debunking the claims and their foreign sources. This also requires more effort by the social media platforms to inform their users by labeling disinformation and calling out falsehoods.  Defending the U.S. will likely also require more direct action by Washington against countries like Iran that increasingly use the internet as a weapon against us.  Gordon Crovitz is co-CEO of NewsGuard and a former publisher of The Wall Street Journal.