An undefined effort to develop the U.S. economy is in the cards for President Donald Trump's administration, he revealed in an interview with Forbes on Tuesday.

"I also have another bill … an economic-development bill, which I think will be fantastic. Which nobody knows about," Trump told Forbes.

Trump says that this was the first time anyone was publicly hearing about the bill, which he defined as "economic-development incentives for companies … to be here." The president said the bill will be, or is, designed to reward companies that keep hiring in the United States.

The president added that companies that send jobs overseas will "get penalized severely" under this new bill.

"It's both a carrot and a stick," he said.

Trump similarly promised on Sept. 27 that the GOP tax reform bill being built will "bring back the jobs and wealth that have left" the country. Unveiled that day, the Republicans' proposal calls for lowering the corporate tax rate to 20 percent from 35 percent.

A White House official told CNBC's Eamon Javers the economic development bill will come after the government passes both tax reform and infrastructure bills. Trump's administration views tax reform as the carrot for companies to stay in the U.S. and the economic development bill as the stick, the official said.

The new economic development bill Trump teased appears to be in addition to the tax reform proposal. Trump said his plan would make it "very tough" for companies who leave and then try to sell products back to the U.S.

NAFTA, the 23-year-old trade agreement with Mexico and Canada, is also on the chopping block in Trump's view.

"NAFTA will have to be terminated if we're going to make it good," Trump told Forbes.

In the same breath, he reiterated statements he has made previously regarding another trade deal, the Trans-Pacific Partnership. Trump called the Trans-Pacific Partnership "a large-scale version of NAFTA," saying "it would have been a disaster." The president formally withdrew the United States from the Trans-Pacific Partnership by executive order on Jan. 23.

U.S. officials began meeting with trade representatives from Canada and Mexico on Aug. 16 to renegotiate NAFTA.

Read the full interview on Forbes here.