President Donald Trump told Iran on Thursday it made a “big mistake” by shooting down a US spy drone, an incident bringing the two countries ever closer to open conflict in the world’s busiest oil shipping lane. “They made a very big mistake,” Trump told reporters at the White House following the strike near the strategic Strait of Hormuz. “This country will not stand for it, that I can tell you,” said Trump. But while one of his top Republican allies said the downing of the drone had taken the two countries “one step closer” to war, Trump simultaneously appeared to play down the incident saying it may not have been unintentional. The Islamic Revolutionary Guard Corps said it had brought down the unmanned Global Hawk surveillance aircraft as it was “violating Iranian air space” over the waters of Hormozgan province. The Pentagon, however, denounced an “unprovoked attack” in international air space, claiming the drone was some 34 kilometers (21 miles) from the nearest point in Iran when it was downed by a surface-to-air missile. Iran vowed in response to go to the United Nations to prove Washington was “lying.” Crude oil prices rose more than six percent after the incident which marked a new peak in tensions as Tehran pushes back against surging US diplomatic, economic and military pressure. Trump has repeatedly said he does not favor war with Iran unless it is to stop the country getting a nuclear weapon — something Iranian leaders insist they are not pursuing. But critics of the Trump administration say that his policy of “maximum pressure” — including crippling economic sanctions, abandonment of a complex international deal to regulate Iran’s nuclear activities, and deployment of extra sea, air and land forces to the region — make war ever more likely. The drone downing came as Iran was already accused by Washington of having carried out explosions on oil tankers in the congested Hormuz area. Tehran denies having been behind the attacks but has frequently threatened in the past to block the sea lanes used by shipping to move much of the world’s oil exports. In Washington, talk of war has become part of the already heated atmosphere as Trump’s reelection fight starts to gain traction. A key Republican ally of Trump, Senator Lindsey Graham, said the president’s “options are running out.” Asked if he believe the countries were edging closer to war, he replied: “I think anybody would believe that we’re one step closer.” “They shot down an American asset well within international waters trying to assess the situation. What are you supposed to do?” One of Trump’s biggest opponents, the Democratic speaker of the House of Representatives, Nancy Pelosi, warned that “there’s no appetite for wanting to go to war in our country.” Russian President Vladimir Putin, who has close relations with Iran’s leadership, said that US military retaliation against Iran “would be a disaster for the region.”