WASHINGTON — The United States announced Wednesday its largest arms sale ever — hundreds of advanced warplanes and helicopters for Mideast ally Saudi Arabia in a deal worth up to US$60 billion. The plan allows for the sale to Riyadh of 84 F-15 fighter jets, 70 Apache attack helicopters, 72 tactical Black Hawk helicopters and several Little Birds, lightweight helicopters often used in special operations, assistant secretary for political-military affairs Andrew Shapiro said. The sale, which also includes the upgrade of 70 used F-15s, is “not to exceed US$60 billion,” Shapiro told reporters. The delivery of the weapons would be spread over 15 to 20 years. U.S. President Barack Obama’s administration officially notified Congress of what Shapiro described as a “significant” arms sale to Riyadh. Congress has the authority to amend or delay the agreement, Shapiro said, adding that he did not expect Israeli opposition to the sale. U.S. defense officials said the deal had been in the works for months with the Saudis, who have grown increasingly anxious about Iran’s missile arsenal. U.S. officials were already speaking about the US$60-billion sale in September. Last month State Department spokesman Philip Crowley said major arms deals to countries like Saudi Arabia and Israel were in the U.S. “national interest” as Washington seeks to keep the region stable and counter potential threats from Iran. Prior to Crowley’s comments, the Israeli government said it had given final approval to the purchase from the United States of F-35 stealth fighter jets, which are “fifth generation” U.S. jets with more advanced technology that F-15s. U.S. officials see the Saudi package as underscoring the strategic alliance between the two countries, despite serious strains over Middle East diplomacy and the aftermath of the September 11, 2001 attacks. In September the officials said the sale was likely to include HARM anti-radar missiles, more precision-guided JDAM bombs, Hellfire missiles and sophisticated displays mounted on fighter pilots’ helmets, but it was not immediately clear if they were part of the deal announced Wednesday.