The exercises, called Eqtedar or "force" in Farsi, began last week and will continue until mid-March. They involve the army and the Islamic Revolution Guards Corps (IRGC), the ideological arm of the Iranian army.
On Tuesday, the IRGC announced that the drills initially targeted the nuclear enrichment plant at Natanz in central Iran.
"The exercises are currently being held at the Fordo and Khondab nuclear facilities" in central and western Iran, respectively, state television reported.
They involve missile and radar units, electronic warfare units, electronic and standard intelligence command, which carry out "offensive and defensive missions," it added.
The military activities are taking place with Iran's nuclear programme under close scrutiny ahead of US President-elect Donald Trump's return to the White House.
During his first term, Trump withdrew the United States from the 2015 nuclear agreement with Tehran and also ordered the killing of an IRGC general in a drone strike in Iraq.
Iran is due to hold nuclear talks with France, Britain and Germany on 13 January in Switzerland.
In January, US news website Axios reported that White House national security adviser Jake Sullivan had presented President Joe Biden with options for a potential US strike on Iran's nuclear facilities if Tehran moves to develop atomic weapons before 20 January, when Trump takes office.
Iranian Foreign Ministry spokesman Esmail Bakai criticized the reports, saying the threats against the country's nuclear facilities were a "flagrant violation of international law."
Iran says its nuclear programme is for peaceful purposes only and denies any intention to develop atomic weapons.
Iran has increased its production of enriched uranium in recent years and is the only non-nuclear-weapon state to possess uranium enriched to 60%, according to the International Atomic Energy Agency's (IAEA) nuclear watchdog.
That level is on track to reach the 90 percent needed to create an atomic bomb. | BGNES
