US defense secretary Lloyd Austin has vowed that the United States will take “all necessary actions” to defend its troops after Iran-backed militants killed three US troops and wounded dozens more in a drone attack on a US base in Jordan. The statement came as US officials told the Associated Press that the enemy drone – which also wounded dozens of people at the desert outpost in Jordan – may have been confused with an American drone returning to the US installation. The attack on Sunday was the first deadly strike against US troops since the Israel-Hamas war erupted in October, and marks a major escalation in tensions that have engulfed the Middle East. “The president and I will not tolerate attacks on US forces and we will take all necessary actions to defend the US and our troops,” Austin said at the Pentagon on Monday. John Kirby, a spokesperson for the National Security Council at the White House, told CBS: “We are not interested in a broader conflict in the region, we’re not looking for another war, but we absolutely will do what we have to do to protect ourselves.” In describing the drone attack, the two US officials, who were not authorized to comment and insisted on anonymity, said preliminary accounts suggest the enemy drone that struck the installation known as Tower 22 may have been mistaken for an American drone that was in the air at the same time. The officials said that as the enemy drone was flying in at a low altitude, a US drone was returning to the base. As a result, there was no effort to shoot down the enemy drone. The possible explanation for how the enemy drone evaded US air defenses on the installation came as the White House said on Monday it was not looking for war with Iran even as Joe Biden vows retaliatory action. The Democratic administration believes Tehran was behind the strike. The attack, which the Biden administration blames on Iranian-based proxies, adds another layer of complexity to an already tense Middle East situation as the Biden administration tries to keep the Israel-Hamas war from expanding into a broader regional conflict. The targeted base, known as Tower 22, sits near the demilitarized zone on the border between Jordan and Syria along a sandy, bulldozed berm marking the DMZ’s southern edge. The Iraqi border is only 10km (6 miles) away. The area is known as Rukban, a vast arid region that once saw a refugee camp spring up on the Syrian side over the rise of the Islamic State group’s so-called caliphate in 2014. The base’s location offers a site for US forces to infiltrate and quietly leave Syria. US troops long have used Jordan, a kingdom bordering Iraq, Israel, the West Bank, Saudi Arabia and Syria, as a basing point. Some 3,000 American troops typically are stationed across Jordan. However, the US presence in Jordan risks angering a population that has already held mass demonstrations against Israel’s war on Hamas in Gaza over civilian casualties in a conflict that has already killed over 26,000 Palestinians.