The Trump administration is keeping alive one of the last remaining components of the 2015 Iran nuclear deal by extending sanctions waivers that allow foreign companies to work with Iran’s civilian nuclear program without US penalties.

The waivers had been due to expire Tuesday but were extended by Secretary of State Mike Pompeo for another 90 days. The extensions were not announced until Thursday.

Pompeo also announced new sanctions on Iran’s construction sector, which he determines to be under the control of the Iranian Revolutionary Guard Corps. The IRGC was designated earlier this year as a “foreign terrorist organization.”

State Department spokeswoman Morgan Ortagus said the move “will help preserve oversight of Iran’s civil nuclear program, reduce proliferation risks, constrain Iran’s ability to shorten its ‘breakout time’ to a nuclear weapon, and prevent the regime from reconstituting sites for proliferation-sensitive purposes.”

Trump withdrew last year from the nuclear deal and has steadily ramped up sanctions on Iran that had been eased under the agreement. But the so-called “civilian nuclear cooperation” waivers will permit European, Russian and Chinese companies to continue to work at Iranian civilian nuclear facilities.

Nuclear deal critics, including Trump allies like Republican Sens. Ted Cruz of Texas and Tom Cotton of Arkansas, have long argued that the waivers should be revoked because they give Iran access to technology that could be used for weapons.