Iran's state television has showed rare footage of a secret underground missile depot.

The state TV released footage Tuesday of a launch site of the long-range "Emad" ballistic missile, which was first test fired in last October, according to Middle East Eye.

National Parliament speaker Ali Larijani was seen in the footage inspecting the Iranian Revolutionary Guard Corps (IRGC)'s newly inaugurated depot, according to DW.

Iran unveiled it's first secret underground missile facility in October last year.

A senior Iranian commander claimed at the time of the first footage's release that Iran has many underground missile depots.

"The Islamic republic's long-range missile bases are stationed and ready under the high mountains in all the country's provinces and cities," said Brigadier General Amir Ali Hajizadeh, commander of the Guards' aerospace division, as HNGN previously reported.

The Islamic republic's missile program has reportedly remained unaffected despite U.N. restrictions and diplomatic pressure. Iran tested three long-range ballistic missiles last October in violation of a United Nations Security Council (UNSC) resolution.

The U.S. has warned Iran of new sanctions in response to the October missile test.

"We are fully prepared to use sanctions with respect to this most recent ballistic missile test [and] are still working through some technical issues there," State Department spokesman John Kirby said Tuesday, according to RFERL.