Secretary of State Mike Pompeo extended the waivers, which were due to expire Saturday, for 90 days, shorter than the 180 days that had been granted in the past. The waivers permit work at several Iranian nuclear sites to continue without U.S. penalties. Under the terms of the 2015 Iran nuclear deal, Russia and several European nations help maintain the facilities and are engaged in converting equipment there for exclusively civilian use.
Facilities included in the waiver extensions include the Bushehr nuclear power plant, the Fordow enrichment facility, the Arak nuclear complex and the Tehran Research Reactor, the State Department said.
However, the Bushehr waiver is being tightened so that any assistance to expand the plant could incur sanctions.
The other two waivers — one that allowed Iran to store excess heavy water produced in the uranium enrichment process in Oman, and one that allowed Iran to swap enriched uranium for raw yellowcake with Russia — were not renewed, the department said. That decision is aimed at forcing Iran to stop enriching uranium, something it was allowed to do up to certain limits under the nuclear deal, it said. Highly enriched uranium can be used to fuel a nuclear weapon.
"Iran must stop all proliferation-sensitive activities, including uranium enrichment, and we will not accept actions that support the continuation of such enrichment," State Department spokeswoman Morgan Ortagus said in a statement. "The United States will continue to impose maximum pressure on the Iranian regime and remains committed to denying Iran any pathway to a nuclear weapon."
President Donald Trump withdrew the U.S. from the Iran nuclear deal last year, re-imposed sanctions that had been eased in November and has steadily ramped up pressure on Iran in the months since.
Last month, his administration announced it would no longer renew sanctions exemptions that allowed China, India, Japan, Turkey and South Korea to continue importing Iranian oil. Those waivers expired Friday, although it was not immediately clear whether the administration would impose sanctions on some or all of those countries if they take delivery of previously purchased oil.
Some hard-liners on Iran in Congress and outside the administration have called for the elimination of all sanctions waivers, including for civilian nuclear cooperation, in order for the administration to make good on its "maximum pressure" campaign.
Supporters of the Iran deal say the cooperation waivers are important to maintain because they give the outside world additional eyes on what Iran is doing in its nuclear facilities.