The site showed the page was “not available” shortly after the scheduled start time of 8pm Eastern US Time on Monday for many users.

“There appears to be a massive DDOS attack on X,” Musk wrote in an X post at 8.18pm, referring to a type of cyber attack in which a server or network is flooded with traffic in an attempt to shut it down.

“Working on shutting it down. Worst case, we will proceed with a smaller number of live listeners and post the conversation later.”

He said minutes later: “We will proceed with the smaller number of concurrent listeners at 8:30 ET and then post the unedited audio immediately thereafter.”

Ahead of Monday’s event, Musk had written: “Am going to do some system scaling tests tonight & tomorrow in advance of the conversation.”

The interview was a fresh opportunity for Trump to seize the limelight at a time when his campaign is facing new headwinds.

His Democratic rival for the November 5 election, Vice President Kamala Harris, has erased Trump’s lead in opinion polls and energised Democratic voters with a series of high-energy rallies. Harris’ momentum could get another boost from the Democratic National Convention next week in Chicago.

Trump returned to X, formerly known as Twitter, on Monday morning for the first time in a year, posting a video highlighting his claim without evidence that the four criminal prosecutions he faces are politically motivated.

He quickly followed with a half-dozen other posts, reviving an account that served as a main method of communication in previous campaigns and his four years in the White House, including his followers’ January 6 2021 attack on the US Capitol.

Trump’s last X message before Monday was posted in August 2023 appealing for donations and showing a mug shot after he was booked at an Atlanta jail in relation to felony charges tied to his attempts to overturn his 2020 election defeat in Georgia.

Trump’s access to his account, @realDonaldTrump, was restored a month into Musk’s ownership of X after being suspended by the platform’s previous owners following the January 6 attack, citing concerns he would incite violence.

Trump frequently posts on his Truth Social platform, which was launched in February 2022, but his posts there reach a much smaller audience than on X.

The interview on Musk’s social media platform allows Trump to reach a different audience than the conservative faithful who attend his rallies and watch his interviews on Fox News.

Some X users also reported seeing advertisements pop up supporting Trump. X and the Trump campaign did not immediately respond to a request for information on whether there had been a pro-Trump ad buy.

Advertisers have fled X since Musk bought it in 2022. X earlier this month sued a global advertising alliance and several major companies, accusing them of unlawfully conspiring to boycott the site and causing it to lose revenue.