Iranian leaders are threatening to restart the country's contested nuclear enrichment program in just a matter of days as the Trump administration and European allies scramble to address a range of flaws in the landmark nuclear accord ahead of a May deadline that could see the United States walk away from the accord, according to regional reports and administration insiders.

The head of Iran's Atomic Energy Organization disclosed on Sunday that the Islamic Republic has maintained the ability to restart the full-scale enrichment of uranium—the key component in a nuclear weapon that was supposed to be removed from Iran as part of the nuclear agreement—in just four days.

Ali Akbar Salehi, head of Iran's atomic work, claimed Iran could enrich uranium to 20 percent, which is more than enough to quickly reach the threshold to power a nuclear weapon, in just four days if the word is given by Iran's hardline ruling regime.