Iran is escalating its fight with the United Nations nuclear watchdog by 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.

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.

Iran’s foreign minister said Tuesday that Tehran will respond to a recent US proposal on the Iranian nuclear program “in the coming days.” “The US proposal contains many ambiguities and questions,” Abbas Araghchi said during a book signing event in the Lebanese capital, Beirut.