The United States warned Wednesday that sanctions against Iran would soon be “increased substantially,” after the International Atomic Energy Agency (IAEA) confirmed that the Islamic Republic had exceeded a limit on enriched uranium in a substantial violation of the 2015 nuclear accord.

“Iran has long been secretly ‘enriching,’ in total violation of the terrible 150 Billion Dollar deal made by John Kerry and the Obama Administration,” U.S. President Donald Trump wrote on Twitter, adding that “the deal was to expire in a short number of years.”

He warned that, “Sanctions will soon be increased, substantially!”

The fear that Iran is secretly set on making a nuclear bomb and may have an undeclared enrichment facility is borne out by history. The enrichment facility at Natanz was only acknowledged by Iran after it was revealed by a dissident group, National Council of Resistance of Iran, in 2002.

Even after the 2015 nuclear agreement with world powers, Iran continued to lie. The Islamic Republic preserved and expanded its nuclear know how for future use, under a different name using the same personnel. Annex I, Section T of the nuclear deal bars Iran from the “development of a nuclear explosive device.” IAEA Director General Yukiya Amano confirmed that his agency can’t verify Section T of Annex I, in part due to the IAEA’s inability to inspect Iranian military sites.

“There is no credible reason for Iran to expand its nuclear program, and there is no way to read this as anything other than a crude and transparent attempt to extort payments from the international community,” the White House said in a statement issued at a closed-door session of the IAEA board in Vienna.

The statement stressed further that, “The United States has made clear that we are open to negotiation without preconditions, and that we are offering Iran the possibility of a full normalization of relations.”