The US Secret Service said Monday it was aware of a post by billionaire Elon Musk on social media platform X that was linked to the assassination attempt on Trump. Platform X owner, ex-Twitter, who is a Trump supporter, soon deleted the tweet, which read:

"And no one is even trying to kill Biden/Kamala." A post he ended with a raised eyebrow face emoticon.

He was quickly criticized by X users on the left and right, who said they were worried his words to his nearly 200 million followers could incite violence against Biden and Harris, reports Reuters. 

Musk deleted the post, but the Secret Service, tasked with protecting current and former presidents, vice presidents and other high-profile officials, took notice.

"The Secret Service is aware of Elon Musk's post on social media, and as a matter of practice, we do not comment on matters involving protective intelligence," a spokesman for the service told Reuters in an email.

"We can, however, say that the Secret Service investigates all threats related to our proteges," the response added.

A spokesman declined to specify whether the agency had contacted Musk, who appeared to suggest in subsequent posts that he was joking.

"Well, one lesson I've learned is that just because I say something to a group and they laugh doesn't mean it's going to be as funny as X's post," he wrote.

"It turns out that jokes are less funny if people don't know the context and the delivery is plain text."

Democratic candidate Harris and incumbent President Biden expressed gratitude that Trump was unharmed and condemned political violence.