While he was campaigning last fall, President Trump bemoaned the lack of a U.S.-backed investment fund and promised to create one.

“Other countries have wealth funds,” he said. “We have nothing.”

On Monday, he took the first step. He issued an executive order that announced the planning for an investment vehicle or a sovereign wealth fund, which would be financed by the United States government.

Sovereign wealth funds are investment funds owned by an individual state or government typically created from budget surpluses or revenues from oil or other commodities. These funds may indirectly finance domestic industries as well as a wide range of other investments.

The order calls for the secretary of the Treasury, Scott Bessent, and the secretary of commerce, Howard Lutnick, to report back with a plan in 90 days. In a news conference on Monday, Mr. Bessent said that the government would create this fund in the next 12 months.

The president and his associates can take their plan only so far. The establishment of a sovereign-wealth fund, which would use taxpayer dollars or other government funds, is likely to require an act of Congress.

It’s unclear how exactly the U.S. government would come up with the money to put into it. While many other countries operate funds that invest domestically and internationally, many of them, particularly those in the Middle East, have significant proceeds from natural resources like oil or gas to invest. Other countries, including Singapore, use their budget surpluses.

By contrast, the U.S. government doesn’t have any significant natural resource revenue and has been operating under an annual budget deficit for more than two decades. Despite a flurry of announcements on tariffs in recent days, neither Mr. Trump, Mr. Bessent nor Mr. Lutnick mentioned the proceeds of these tariffs as a source of funding.

In September during a speech at the Economic Club of New York, Mr. Trump pointed to “money that will be taken in through tariffs” as one key source of funding, along with “other intelligent things.”

In a fact sheet accompanying the order, Mr. Trump’s team cited $5.7 trillion in assets held by the federal government and added that the government holds even more “indirectly, including through natural resource reserves.”

According to the Treasury Department’s website, as of 2023, the government had $5.3 trillion. Of that, the United States held roughly $922.2 billion in cash, which is mostly used to run its operations. It held $423.0 billion in so-called inventory, most of it from the Department of Defense, which includes stockpiles of commodities or equipment like ammunition and tactical missiles. It had $1.7 trillion in outstanding loans made by government agencies like the Department of Education and the Small Business Association; and another $1.2 trillion in assets like land, buildings, structures, facilities and software.

It’s unclear how those trillions of dollars could flow into a sovereign wealth fund. The U.S. government has relied on ever larger amounts of borrowed money and is projected to run budget deficits long into the future.

Mr. Lutnick speculated that the government could take stakes in TikTok or private companies it works with. He cited government funding for Covid-19 vaccines as an example. “If we are going to buy two billion Covid vaccines, maybe we should have some warrants and some equity in these companies,” Mr. Lutnick said.

There are more than 100 sovereign wealth funds around the world with combined assets valued at over $10 trillion. According to the Sovereign Wealth Fund Institute, at least 40 sovereign funds have been created since 2005.

Saudi Arabia’s fund, the Public Investment Fund, has been among the more active and high-profile funds in recent years. It made a splash by investing $40 billion in SoftBank’s Vision Fund that then poured money into technology startups all over the world, including the troubled real-estate company WeWork.

The PIF, as it is known, said it had roughly $925 billion in assets under management.

On Monday, Mr. Trump pointed to the PIF, saying, “The Saudi Arabia fund is on the large side, but eventually we’ll catch it.”