FILE PHOTO: U.S. Energy Secretary Rick Perry addresses the media in Mexico City, Mexico July 13, 2017. REUTERS/Henry Romero

HOUSTON (Reuters) - U.S. Energy Secretary Rick Perry said on Wednesday he was “not sure” if President Donald Trump had made up his mind about levying tariffs on imported steel and aluminum.

Trump wants to protect American workers against countries that engage in unfair trade practices, but “I’m not sure he has made up his mind” on the tariffs, Perry said on the sidelines of the CERAWeek energy conference.

The key issue for the administration was putting together a plan that “strategically” deploys tariffs and regulations, said Perry, who addressed conference executives on the global role of a U.S. energy resurgence.

The proposal, which involves imposing a 25 percent tariff on steel and 10 percent on aluminum, has been criticized by Republican lawmakers and U.S. trade allies since the president first tweeted his intentions last week.

Gary Cohn, the president’s top economic adviser and a free trade advocate, resigned on Tuesday in a sign of an internal clash on the issue within the administration.

Perry suggested the proposal could unleash a backlash that draws in other sectors.

“If you change one rule, it probably has an effect. Does it have unintended consequences? It may do that.”