China on Monday said "unilateral bullying" by the U.S. was the cause behind the escalating Iran nuclear crisis, after Tehran announced it was set to breach its uranium enrichment cap. "The facts show that unilateral bullying has already become a worsening tumor," said Chinese Foreign Ministry spokesman Geng Shuang at a press briefing in Beijing. "The maximum pressure exerted by the U.S. on Iran is the root cause of the Iranian nuclear crisis," he said.

Iran will initially enrich its uranium to a concentration of 4.5 percent, surpassing the limit set in the 2015 nuclear agreement, the country's nuclear agency said yesterday. "Our facilities require a concentration of between 1.1 and 4.5 percent, therefore below 5 percent will suffice for the time being," according to Behrouz Kamalvandi, a spokesman for the agency. The announcement comes a day after Tehran said it had begun its uranium enrichment level beyond the 3.67 percent threshold agreed in the deal struck with world powers. It marks the second breach of the nuclear deal by Iran in a week. Tehran said last Monday it had also exceeded the limit of 300 kilograms of low-enriched uranium it is allowed to stock. The announcement has stirred fears in Western countries amid growing tensions in the region.

Iran also threatened yesterday to break a third term in the agreement by reversing the reconfiguration of a heavy-water reactor so it is once again capable of producing plutonium. Iran's Foreign Ministry said it would take the step in 60 days if the remaining parties do not find ways to counter U.S. sanctions against Tehran.

President Donald Trump last year pulled the U.S. out of the accord and began imposing a "maximum pressure" campaign of strict sanctions on Tehran, over the objections of his European allies. The remaining powers in the agreement, including Britain, France and Germany, have sought to keep it alive by developing a money transaction system known as Instex that allows Iran to circumvent U.S. sanctions and continue doing business with international partners. Iran has said multiple times that even if it does pull out of the nuclear agreement, the country has no intention of developing nuclear weapons.