Iran staged military exercises late last year and again this week
An Iranian military commander has said Iran would take pre-emptive action against its enemies if it felt its national interests were endangered.
Mohammad Hejazi, deputy head of Iran's armed forces, made his comments to the Iranian Fars news agency.
Iran is facing mounting international pressure over its controversial nuclear programme.
On Monday it unveiled fresh military exercises in the south that it said was to protect its nuclear sites.
"Our strategy now is that if we feel our enemies want to endanger Iran's national interests, and want to decide to do that, we will act without waiting for their actions," Mr Hejazi told Fars.
The BBC's Iran correspondent James Reynolds says Iran's military and political leaders routinely stress that they are capable of defeating the country's enemies should the need arise.
Their comments are closely scrutinised by those trying to work out Iran's military capability and also its overall intentions, he adds.
Iran insists its uranium enrichment programme is for peaceful purposes but Western powers suspect Tehran intends to make weapons.
Neither Israel nor the US have ruled out military action if sanctions and diplomacy fail to rein in Iran's nuclear activities.
In recent weeks speculation has been increasing that Israel may launch a military strike on Iran's nuclear facilities.
Last week, US Defense Intelligence Agency director Lt Gen Ronald Burgess told the US Congress that Iran may launch missiles if it is attacked but was unlikely to initiate or intentionally provoke a conflict.
On Monday senior inspectors from the UN's International Atomic Energy Agency (IAEA) began another round of talks in Tehran - their second in three weeks.
They say they want Iranian reassurances about "possible military dimensions" to the nuclear programme.
Late last year Iran conducted 10 days of military exercises near the Strait of Hormuz at the entrance to the Gulf.
Iran has threatened to block the strait, through which 20% of the world's oil exports pass, in retaliation for Western sanctions over its nuclear plans.