Iran’s president Hassan Rouhani warned Europeans nations Wednesday that Tehran will “take the next step” in increasing its uranium enrichment closer to weapons-grade levels this coming Sunday if they do not offer a new deal by then.

Senior officials from Iran and the remaining signatories to its 2015 nuclear deal with world powers are gathering Friday as tensions in the Persian Gulf simmer and Tehran is poised to surpass a uranium stockpile threshold, posing a threat to the accord.

Iran will speed up enrichment of uranium after a deadline given to European countries to prevent this ends on Thursday, the spokesman for Iran’s Atomic Energy Organization said on Wednesday, according to the IRIB news agency.

Iranian officials slammed the Trump administration Tuesday for new sanctions targeting the country’s leadership, saying the measures permanently closed the path to diplomacy and that the White House had “become mentally crippled” under the current president.

President Donald Trump on Monday announced new sanctions targeted at Iran’s top leadership and those thought responsible for downing a US drone flying near the country.