Iran's elite Revolutionary Guards unveiled an underground missile base at an undisclosed Gulf location on Friday, Iranian state media reported, at a time of heightened tension between Tehran and the United States."The base is one of several bases housing the Guards' Navy's strategic missiles," the state media quoted the head of the Guards, Major General Hossein Salami, as saying. Last year, the Guards said Iran had built underground “missile cities” along the Gulf coastline, warning of a “nightmare for Iran’s enemies”. "These missiles have ranges of hundreds of kilometers, enjoy pinpoint accuracy and huge destructive power, and can overcome the enemy’s electronic warfare equipment," Salami said.He said the base was "one of several bases housing the Navy’s strategic missiles."There have been periodic confrontations in the Gulf in recent years between the Guards and the US military, which has accused the Guards’ navy of sending fast attack boats to harass US warships as they pass the Strait of Hormuz.Tensions have been high between Tehran and Washington since 2018, when President Donald Trump exited the 2015 nuclear deal between Iran and six world powers which limits the Islamic Republic's nuclear program and reimposed sanctions that have crippled the country's economy. Iran's parliament passed a law in November that obliges the government to halt inspections of its nuclear sites by the International Atomic Energy Agency and to step up uranium enrichment beyond the limit set under Tehran's 2015 nuclear deal if the US sanctions are not eased.Iran's Guardian Council watchdog body approved the law on Dec. 2 and the government has said it will implement it.Iran will expel United Nations nuclear watchdog inspectors unless sanctions are lifted by a Feb. 21 deadline set by the hardline-dominated parliament, a lawmaker said on Saturday. "According to the law, if the Americans do not lift financial, banking and oil sanctions by Feb. 21, we will definitely expel the IAEA inspectors from the country and will definitely end the voluntary implementation of the Additional Protocol," said parliamentarian Ahmad Amirabadi Farahani.The comments, referring to texts governing the IAEA's mission and activities, were carried by several Iranian media outlets.Iran said on Monday it had resumed 20% uranium enrichment at an underground nuclear facility, breaching the nuclear pact with major powers and possibly complicating efforts by U.S. President-elect Joe Biden to rejoin the deal. It began violating the accord in 2019 in response Trump's withdrawal from the Iran deal in 2018 and the reimposition of US sanctions lifted under the deal.Tehran often says it can quickly reverse its breaches if Washington's sanctions are removed.Tovah Lazaroff contributed to this report