President Donald Trump is allowing chemical makers, coal-fired power plants and other facilities to bypass a range of environmental regulations on grounds that the waivers are needed for national security purposes.

The plants, which also include taconite iron ore processing operations and chemical manufacturing facilities that play a role in the production of semiconductors and energy, were granted two-year waivers from Environmental Protection Agency rules via proclamations signed by Trump and released on Thursday evening. The rules were finalized under the previous Biden administration.

“The exemptions ensure that these facilities within these critical industries can continue to operate uninterrupted to support national security without incurring substantial costs to comply with, in some cases, unattainable compliance requirements,” the White House said in a statement.

Among the exempted operations were taconite iron ore plants in Minnesota owned by the United States Steel Corp. and six facilities owned by Cleveland-Cliffs Inc. in Minnesota and Michigan, according to the White House, which said the steel was used in national defense systems and other critical infrastructure.

Chemical makers, including Dow Inc. and BASF SE, and refiners such as Phillips 66 and Citgo Petroleum Corp., were granted waivers from EPA regulations requiring emissions controls for certain facilities, according to the White House, which said the requirements would have required massive capital investments or even forced the plants to shut down.

The White House also said coal-fired power plants in Ohio, Illinois and Colorado had been exempted from stringent air pollution mandates limiting the emission of mercury and other toxins.

The Biden “emissions standards impose costly and, in some cases, unattainable compliance requirements on these industries essential to national interests,” according to a White House fact sheet.

The waivers follow guidance earlier this year by the EPA that said companies could ask for exemptions to a range of regulations for as long as two years.

— With assistance from John Harney