U.S., European and Iranian officials meet Tuesday in Vienna, a last opportunity for the Obama administration to bolster the Iranian nuclear agreement along with its partners before President-elect Donald Trump takes office; reported.

The officials are meeting under the aegis of the so-called Joint Commission, comprised of representatives of Iran and the six world powers who negotiated the July 2015 nuclear deal. The commission oversees the implementation of the accord and arbitrates disputes among the signatories.

In recent months, the Commission has approved decisions to exempt some Iranian nuclear material from the country’s stockpile limits and sought to shore up the agreement with measures to ensure Iran doesn’t breach the terms of the nuclear accord by exceeding caps on material such as uranium and heavy water.

During the U.S. presidential campaign, Mr. Trump repeatedly attacked the accord, a key foreign-policy legacy of the Obama administration. After the Nov. 8 election, U.S. officials said they were looking for ways to help secure the agreement.

Among the issues set for discussion Tuesday are Iranian complaints about the decision last month by U.S. Congress to extend nonnuclear U.S. sanctions on Tehran, according to diplomats.

The meeting may also address the decision by the six powers to allow Iran to import large amounts of natural uranium. On Monday, Western diplomats confirmed that the U.S. had backed a request by Russia to export more than 100 tons of natural uranium to Iran. A second export request by Kazakhstan is pending, they said.

Despite reservations in some European capitals, the decision to approve the Russian uranium export request was supported by the U.S. administration, according to several Western diplomats. It must still be confirmed by the United Nations Security Council.

In its natural form, uranium isn’t useful in a nuclear program, but it can be enriched to produce fuel for a nuclear weapon. White House press secretary Josh Earnest said Monday that “any sort of uranium that’s held by the Iranian government will be subject to very strict limits.”

U.S. officials say Iran could use the uranium from Russia to fuel its nuclear power plant at Bushehr. Iran was required to submit plans for use of the material, which will be monitored, the officials say, for the next 25 years.

Under the nuclear deal, Iran is limited to a stockpile of low-enriched uranium of 300 kilograms, about 660 pounds, for the next 15 years—a key part of the deal designed to ensure that until at least 2026, it will take Iran over a year to accumulate enough material for a nuclear weapon.

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