US Secretary of State Mike Pompeo on Saturday accused Iran of launching attacks on Saudi oil plants, ruling out the involvement of the Tehran-aligned Houthi militias in Yemen. The Houthis claimed credit for the attacks on the Abqaiq plant -- Aramcos largest oil processing facility -- and nearby Khurais. Pompeo dismissed the claim and firmly placed blame on Iran. “Tehran is behind nearly 100 attacks on Saudi Arabia while Rouhani and Zarif pretend to engage in diplomacy,” Pompeo said, referring to Iran’s President Hassan Rouhani and Foreign Minister Mohammed Javad Zarif. “Amid all the calls for de-escalation, Iran has now launched an unprecedented attack on the world’s energy supply,” he added. “We call on all nations to publicly and unequivocally condemn Iran’s attacks,” Pompeo said, warning that the Trump administration would work with its allies to make sure Iran was “held accountable for its aggression.” The tweets signaled a more hawkish stance in Washington toward Tehran, following signs of a possible thaw in relations between the two nations after months of escalation. Last year, US President Donald Trump withdrew the United States from a 2015 pact that aimed to keep a lid on Tehran’s nuclear ambitions and he has imposed a series of sanctions that have crippled Iran’s economy. But in recent weeks, Trump has said he would be open to meeting with Rouhani, perhaps on the sidelines of the United National General Assembly in New York later this month. Pompeo has said such talks could take place without any preconditions. Rouhani, for his part, has said that Tehran, which denies seeking nuclear weapons, would not talk to the United States until Washington lifts the sanctions. Republican Senator Lindsay Graham, a close Trump ally and a member of the Senate Foreign Relations Committee, said Saturday’s attacks showed Iran was not interested in peace and was instead pursuing nuclear weapons and regional dominance. “It is now time for the US to put on the table an attack on Iranian oil refineries if they continue their provocations or increase nuclear enrichment,” Graham said on Twitter. The White House said the United States was committed to keeping oil markets well-supplied in the wake of the attack and the US Energy Department said the administration could release oil from strategic reserves if necessary.