Iran warned Tuesday that it is capable of resuming high-level uranium enrichment—up to 20 percent—within five days. This degree of enrichment can be used in a nuclear weapon.

“If we make a determination, at most in five days we can start 20-percent enrichment in Fordo (the site of an Iranian nuclear plant),” the head of Iran’s Atomic Energy Organization, Ali Akbar Salehi, told Iranian media.

Salehi’s comments follow a warning last week by Iranian President Hassan Rouhani that the Islamic Republic could abandon its 2015 nuclear agreement with world powers “within hours” if the U.S. follows through with imposing new sanctions on Iran. The nuclear deal stipulates that Iran must cap its uranium enrichment at 3.5 percent.

In early August, President Donald Trump signed new sanctions against Iran over its ballistic missile program and human rights violations. The sanctions were enacted amid Iran’s reported fueling of the recent Temple Mount crisis in Israel, as well as the Islamic Republic’s agreement to bolster relations with the Palestinian terror group Hamas.