The so-called “golden dome” would be a missile-defense system similar to Israel’s Iron Dome, and would intercept projectiles launched at the U.S. using satellites. According to President Trump, who gave more details on the project Tuesday, the ambitious effort is meant to build upon Ronald Reagan’s proposed, yet never completed, SDI, or “Star Wars” system, imagined as a defense against missile threats from the USSR.

The dome will be completed in three years, by the end of Trump’s term, and will cost an estimated $175 billion, he claimed. Yet, a recent study by the Congressional Budget Office estimated the project could cost $161 billion at the low end and $542 billion at the high end over two decades.

“Once fully constructed, the golden dome will be capable of intercepting missiles even if they are launched from other sides of the world, and even if they are launched from space,” Trump said in a press conference Tuesday.

In two posts on X from April, Elon Musk denied that SpaceX was involved with Trump’s golden dome project. In response to a post promoting the news reported by Reuters, Musk said “This is not true.” 

In an earlier post, Musk had said he preferred other companies take up the golden dome project.

“SpaceX has not tried to bid for any contract in this regard. Our strong preference would be to stay focused on taking humanity to Mars. If the President asks us to help in this regard, we will do so, but I hope that other companies (not SpaceX) can do this,” he wrote.

Palantir, Anduril, and SpaceX did not immediately reply to Fortune’s request for comment.

Although plans for the missile-defense system are in early stages and may change, the White House is reportedly considering a partnership between SpaceX, Anduril, and Palantir, three companies whose cofounders have previously supported Trump, as frontrunners to build key parts of the system, six sources familiar with the matter told Reuters. 

The three companies met with Trump administration officials over the past several weeks to present their proposal, which includes launching anywhere from 400 to more than 1,000 satellites into space to track missiles. An additional 200 attack satellites equipped with their own missiles or lasers would be responsible for taking down enemy projectiles, Reuters reported. SpaceX would not be directly involved with the weaponization of the satellites, sources told the outlet.

SpaceX has reportedly pitched the idea of the U.S. government paying a subscription service for the government to access the technology, rather than own it, for it to be developed faster, Reuters reported. Pentagon officials have reportedly expressed concern about the idea of not owning the missile defense system outright, which would be unusual for such a large defense system.

Elon Musk, the CEO of SpaceX, is a close advisor to President Trump and donated more than a quarter of a billion dollars to his reelection campaign. As the face of Trump’s Department of Government Efficiency (DOGE), Musk has spent the last months slashing government spending, with around $170 billion in savings made so far, according to the DOGE website. (His original goal was to cut $2 trillion.)

At the same time, Musk’s company SpaceX has made billions of dollars in revenue from government contracts. The space company was awarded more than 300 contracts worth $3.8 billion last year, the New York Times reported.

Musk’s role in the government has reportedly had an influence over the golden dome pitching process, according to one of the sources familiar with the talks. 

“There’s an attitude that the national security and defense community has to be sensitive and deferential to Elon Musk because of his role in the government,” the source told Reuters.

Palantir, the big-data software company, was cofounded by Peter Thiel, who was a major Trump supporter during his first run for president in 2016, donating more than $1 million to pro-Trump groups and serving on the president’s transition team. While Thiel stepped back from his political involvement and donations in 2020 and 2024, Trump chose his protégé JD Vance as his running mate. Palantir CEO Alex Karp describes his politics as populist-left but has previously supported both Republicans and Democrats in congressional elections, according to OpenSecrets. He donated $360,000 to former President Joe Biden during his presidential campaign in 2024. Karp later supported former vice president Kamala Harris for president.

Palmer Luckey, the founder of Oculus (which Facebook purchased for $2 billion in 2014), is also cofounder of Anduril, the country’s largest private-defense startup. Luckey has supported Trump since his first run for president in 2016. At the time, Luckey donated $10,000 to a pro-Trump political group, which he claimed led to him being fired by Facebook in 2017 and being ostracized by his liberal colleagues in Silicon Valley.

In 2020 and 2024, Luckey hosted and co-hosted fundraisers to support Trump’s campaign for president, and personally donated $400,000 to his most recent reelection campaign, Fortune previously reported. The 32-year old Anduril cofounder has been a major supporter of Trump’s defense strategy, and his company has more than $1 billion in military contracts, Fortune also reported previously.