The killing of Iranian military commander Qassim Soleimani by a U.S. airstrike in Iraq has prompted strong interest on social media, with the term “World War 3” trending on Twitter. Many users talked about the prospect of a military draft if the U.S. decides to engage in war with Iran.

“Young people just crashed the Selective Service’s website because they’re terrified of being drafted for World War 3,” American political consultant Frank Luntz tweeted. “The U.S. hasn’t implemented a military draft since 1973.”

Young Americans may be visiting the Selective Service’s website in order to figure out how to unregister themselves for the draft. Registration is mandatory for all American men between the ages of 18 and 25. Registration is also necessary to receive federal student aid to attend college, with FAFSA also trending on social networks. FAFSA stands for Free Application for Federal Student Aid.

Some users joked about blocking the U.S. military on social media in order to evade a possible draft.

Other users commented on the significance of Soleimani’s killing. “The last time the United States killed a major military leader in a foreign country was during World War II, when the American military shot down the plane carrying the Japanese admiral Isoroku Yamamoto,” New York Times National Security reporter Adam Goldman tweeted.

The killing of Soleimani has so far had major repercussions, with the Iraqi parliament voting for U.S. troops to withdraw from Iraq on Sunday. Iran also said it would no longer maintain any of its commitments under the 2015 Iran nuclear agreement, known as the Joint Comprehensive Plan of Action (JCPOA).

Another trending term on social media networks was “Franz Ferdinand,” referring to the Archduke Franz Ferdinand of Austria, whose 1914 assassination in Sarajevo, is considered the main trigger for World War I. Users might have been discussing Ferdinand's case to compare it with the killing of Soleimani. Scottish rock band Franz Ferdinand, which was named after the historical figure, tweeted: “For the record, we think #WWIII is a bad idea.”