Iran is escalating its fight with the United Nations nuclear watchdog, accusing its inspectors of slander and presenting sloppy evidence, according to a legal brief compiled by the Islamic Republic and circulated among diplomats days before a key meeting in Vienna.

Iran has dramatically increased its stockpile of uranium needed to create nuclear weapons and has fallen short of compliance with international regulators, according to an IAEA report.

An outline by the Trump administration would allow Iran to continue enriching uranium at low levels while a broader arrangement is worked out that would block the country’s path to a nuclear weapon.