US President Donald Trump threatened on Wednesday to ratchet up sanctions on Iran and again denounced the 2015 nuclear deal Iran signed with world powers. Trump pulled the US out of the deal, which offered sanctions relief if Tehran curbed its nuclear program. Iran had been complying with the deal, but on Sunday increased its uranium enrichment beyond limits in the deal. Iran has long been secretly enriching, in total violation of the terrible 150 Billion Dollar deal made by John Kerry and the Obama Administration," Trump said on Twitter. "Remember, that deal was to expire in a short number of years. Sanctions will soon be increased, substantially!" The deal confines enrichment in Iran to its Natanz site, which was itself exposed in 2003. Any clandestine enrichment elsewhere would be a grave breach of the deal. In the past two weeks Iran has breached two limits pivotal to the 2015 deal, which aimed to extended the time Iran would need to obtain enough fissile material for a nuclear weapon, if it chose to do so, to a year from around 2-3 months. "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," said a Trump administration statement issued at the closed-door session of the International Atomic Energy Agency (IAEA) 35-nation Board of Governors in Vienna. "We call on Iran to reverse its recent nuclear steps and cease any plans for further advancements in the future. 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."