Elon Musk and Donald Trump now own rival social networks. Here's a timeline of their rocky relationship.

• Former President Donald Trump said he's "very happy" that Elon Musk now owns Twitter.
• The two businessmen have had a tumultuous relationship over the years.

One of the biggest question marks about Elon Musk's takeover of Twitter is whether or not former President Donald Trump will return to the platform.

With his announcement on Tuesday to run for president in 2024, Trump may stand to benefit to regain unfettered access to millions of Twitter users.

Musk has said he'd reverse Trump's ban, but Trump doesn't seem eager to direct focus away from his own social-media startup, Truth Social. And besides, although the two businessmen share a disdain for the left and a tendency toward online bluster, their relationship hasn't exactly been smooth-sailing over the years.

November 2016: Musk says Trump is 'not the right guy' for the job

Just before the 2016 presidential election, Musk told CNBC he didn't think Trump should be president.

"I feel a bit stronger that he is not the right guy. He doesn't seem to have the sort of character that reflects well on the United States," Musk said.

The billionaire added that Hillary Clinton's economic and environmental policies were the "right ones."

December 2016: Musk appointed to Trump's advisory councils

After he won the presidency, Trump appointed Musk to two economic advisory councils, along with other business leaders like Uber CEO Travis Kalanick.

Musk got flack for working with the controversial president, but defended his choice by saying he was using the position to lobby for better environmental and immigration policies.

—Elon Musk (@elonmusk) February 3, 2017

June 2017: Musk cut ties with the White House in protest of Trump's environmental policies

On June 1, 2017, after Trump announced the US would pull out of the Paris Agreement on climate change, Musk resigned from his roles on presidential advisory boards.

"Climate change is real. Leaving Paris is not good for America or the world," Musk said in a tweet announcing his departure.

—Elon Musk (@elonmusk) June 1, 2017

Musk's goal for Tesla is to curb dependence on fossil fuels through electric vehicles, solar power, and stationary energy storage.

January 2020: 'One of our great geniuses'

During a January 2020 interview with CNBC, Trump praised Musk's accomplishments and intelligence.

"You have to give him credit," the former president said, referring to Tesla becoming more valuable than Ford and General Motors. "He's also doing the rockets. He likes rockets. And he's doing good at rockets too, by the way."

Trump went on to call Musk "one of our great geniuses" and likened him to Thomas Edison.

May 2020: Trump backs up Musk in feud with California covid rules

As the pandemic gripped the US in early 2020, Musk clashed with California public-health officials who forced Tesla to temporarily shut down its factory there. Trump voiced his support for Musk.

"California should let Tesla & @elonmusk open the plant, NOW," Trump tweeted in May 2020. "It can be done Fast & Safely!"

"Thank you!," Musk replied.

May 2022: Musk said he would reinstate Trump's Twitter account

In May, Musk said he would unban Trump as the Twitter's new owner.

Musk called the ban a "morally bad decision" and "foolish to the extreme" in an interview with the Financial Times. Twitter kicked Trump off of its platform following the January 6, 2021 attack on the US Capitol.

The Tesla billionaire has called himself a "free speech absolutist," and one of his key goals for taking Twitter private was to loosen content moderation.

July 2022: Trump calls Musk a 'bullshit artist'

In July, Trump took aim at Musk, claiming the businessman voted for him but later denied it.

"You know [Musk] said the other day 'Oh, I've never voted for a Republican,'" Trump said during a Saturday rally in Anchorage, Alaska. "I said 'I didn't know that.' He told me he voted for me. So he's another bullshit artist."

On Monday, Musk tweeted that Trump's claim was "not true."

July 2022: Musk says Trump shouldn't run again

Musk stopped short of attacking Trump personally, but said he shouldn't run for president again.

"I don't hate the man, but it's time for Trump to hang up his hat & sail into the sunset. Dems should also call off the attack – don't make it so that Trump's only way to survive is to regain the Presidency," he tweeted.

He continued: "Do we really want a bull in a china shop situation every single day!? Also, I think the legal maximum age for start of Presidential term should be 69." Trump is 76 years old.

July 2022: Trump lashes out

Trump then went on the offensive, posting a lengthy attack on Musk on Truth Social, the social media company he founded.

"When Elon Musk came to the White House asking me for help on all of his many subsidized projects, whether it's electric cars that don't drive long enough, driverless cars that crash, or rocketships to nowhere, without which subsidies he'd be worthless, and telling me how he was a big Trump fan and Republican, I could have said, 'drop to your knees and beg,' and he would have done it," Trump said in a post that criticized two of Musk's ventures, Tesla and the rocket company SpaceX.

"Lmaooo," Musk responded on Twitter.

October 2022: Trump cheers Musk's Twitter deal, but says he won't return

Following Musk's official buyout of Twitter on Thursday, Trump posted to Truth Social cheering the deal.

"I am very happy that Twitter is now in sane hands, and will no longer be run by Radical Left Lunatics and Maniacs that truly hate our country," he said. He added that he likes Truth Social better than other platforms, echoing comments from earlier this year in which he ruled out a return to Twitter.

On Monday, Musk joked about the potential of welcoming the former president back to his newly acquired platform.

"If I had a dollar for every time someone asked me if Trump is coming back on this platform, Twitter would be minting money!," the Tesla CEO tweeted.