The Trump administration is not going to perpetually extend the steel and aluminum tariff exemptions granted to allies on Monday, Commerce Secretary Wilbur Ross said Tuesday.

On May 1, the White House said it would extend the deadline for the tariff exemptions for the European Union, Canada, and Mexico from May 1 to June 1. The White House said it had reached deals for permanent exemptions for Australia, Argentina, and Brazil.

In a CNBC interview, Ross described the negotiations between the U.S. and the EU as “potentially fruitful discussions,” indicating he was “hopeful” a deal could be reached to permanently exempt the EU from the tariffs. He said the progress made so far justified the extension of the deadline.

Ross insisted, however, that the administration would not keep delaying the implementation of the tariffs.

“If we’re going to impose it, we’re going to have to do it very soon, or else people will start gaming the system,” Ross said. He said the administration had “no intention” of granting protracted extensions of the exemptions.

Ross was the opening speaker at the Milken Institute Global Conference Tuesday morning. He told the assembled crowd of financiers there were “lots of clear signs” that the U.S. economy is “doing very, very well.”

“Reshoring”– the practice of companies bringing manufacturing jobs back to the U.S.– was up 50 percent, Ross told the conference. He cited deregulation and tax cuts as bolstering the U.S. economy.