In the aftermath of the US drone strike that killed the Iranian general Qassem Suleimani in Baghdad, the phrase “World War III” began trending on social media.

More startlingly, a US government agency which registers young men for a potential military draft saw its website crash.

“Due to the spread of misinformation,” the Selective Service System (SSS) tweeted on Friday, “our website is experiencing high traffic volumes at this time … We appreciate your patience.”

It added that it was “conducting business as usual” and emphasised that a return to the draft is not imminent: “In the event that a national emergency necessitates a draft, Congress and the president would need to pass official legislation.”

On Saturday, as Twitter panic subsided, the SSS website was up and running, if slowly.

The US first drafted soldiers during the civil war in the 1860s, prompting deadly, racist riots. A hundred years later, opposition to conscription fuelled protests against the Vietnam war. There has been no draft since 1973.

“I think it’s fair to say that the draft has never been wildly popular,” Jennifer Mittelstadt, a history professor at Rutgers University in New Jersey, told the New York Times.

Experts including Mittelstadt, however, have said reinstating the draft might in fact help build a more inclusive society.

Should the US and Iran go to war, America’s fighting will be done by its volunteer military, about 1.3 million strong and dominated in the enlisted ranks by recruits from working-class and minority groups.

Writing for the Guardian in 2014, the long-serving New York Democratic congressman Charles Rangel said: “The same familiar faces have served multiple tours in Iraq and Afghanistan. A more inclusive military draft … would compel everyone in the nation to stop and rethink about who we send to wars, how we fight – and why we fight them at all.”

All American men aged 18 to 25 are required by law to register with the SSS. Many do so when applying for a driver’s license or applying for student loans. Those who do not register cannot receive federal financial aid or work for the federal government.

The agency says it has registered 91% of eligible men. Despite playing an increasing role in the US military and filling combat roles, women are not required to register.

A return to the draft may remain unlikely, but the SSS says it is prepared to “rapidly provide personnel in a fair and equitable manner while managing an alternative service program for conscientious objectors”.

According to the agency’s website: “Current plans are frequently tested, evaluated, and revised as necessary.

“If implemented, they will guide the Selective Service System in making a smooth transition from current reduced readiness levels to full conscription within six months.”