Iran’s Revolutionary Guard on Wednesday launched underground ballistic missiles at a mock-up US aircraft carrier in the Strait of Hormuz. The exercise highlighted Tehran's network of subterranean bases and drone footage captured by the Guard showed two missiles blasting out from positions in the desert early in the morning. It came a day after two US military bases in the Middle East were put on heightened alert following an Iranian missile threat, with intelligence indicators showing an Iranian missile possibly headed that way. Personnel were told to take cover but no missile struck. Wednesday’s launch from what appears to be central Iran’s desert plateau comes amid heightened tension between Tehran and the US over its tattered nuclear deal with world powers and as sanction pressures grow. “We have carried out the launch of ballistic missiles from the depths of the earth for the first time,” Gen Amir Hajizadeh, commander of the Guard’s aerospace division, told state TV. “That means without using conventional launch pads, the buried missiles suddenly rip out of the earth and hit their targets precisely.” The Guard did not identify the location of the launch, nor the missiles involved. The launch came six months after the Guard shot down a Ukrainian jetliner and killed all 176 people on board. On Monday, Iran towed the mock aircraft carrier to the Gulf waters near the Strait of Hormuz. The US Navy said the exercise was “irresponsible and reckless”. "The US Navy conducts defensive exercises with our partners promoting maritime security in support of freedom of navigation, whereas Iran conducts offensive exercises, attempting to intimidate and coerce,” a Navy representative said. Adm Ali Tangsiri, the Guard’s naval chief, said its armed drones attacked the bridge of the fake carrier on Wednesday, the semi-official Tasnim news agency reported. Tasnim published a graphic overnight that altered the image of an American carrier into the shape of a casket with a set of crosshairs on it. The caption quoted supreme leader Ayatollah Ali Khamenei pledging to seek revenge for the US drone strike that killed a top Iranian general in January. Brian Hook, the US special representative for Iran, was in London on Wednesday to meet Foreign Office officials as part of his attempt to drum up support for extending a UN arms embargo on Iran. Mr Hook said the US would soon be publishing its draft resolution to put to the UN Security Council.