Iran on Sunday began large-scale air defense war games aimed at protecting its nuclear facilities from attack, state TV reported, as an air force commander boasted the country could deter any military strike by Israel. It said the five-day drill will cover an area a third of the size of Iran and spread across the central, western and southern parts of the country. Gen. Ahmad Mighani, head of an air force unit in charge of responding to threats to Iran's air space, said Saturday the war games would cover regions where Iran's nuclear facilities are located. The drill involves Iran's elite Revolutionary Guard, the paramilitary Basij forces affiliated with the Guard as well as army units. The United States and its European allies accuse Iran of embarking on a nuclear weapons program. Iran denies the charge and insists the program is only for peaceful purposes. Israel has not ruled out military action to stop Iran from obtaining nuclear weapons. The commander of the Guard's air force, Gen. Amir Ali Hajizadeh, meanwhile sought on Sunday to play down the significance of Israel's threats against his country, saying they amounted to psychological warfare. "We are sure they are not able to do anything against us since they cannot predict our reaction," Hajizadeh was quoted as saying by the Guard's official Web site, Sephahnews. "If their fighter planes could escape from Iran's air defense system, their bases will be hit by our devastating surface-to-surface missiles before they land," he said. Also on Sunday, Iran's defense minister, Gen. Ahmad Vahidi, said Iran planned to pursue designing and producing its own air defense missiles, according to the official IRNA news agency. His comments were apparently in response to the delay in the delivery from Russia of S-300 anti-aircraft missiles, meant to be a key component of Iran's air defense. Iran complains that the delay is apparently the result of Israeli and US pressure. Israel and the United States have opposed the missile deal out of fear Iran could use the system to significantly boost air defenses at its nuclear sites - including its main uranium enrichment plant at Natanz. Commenting on this week's war games, a senior Obama administration official urged Iran to engage with the international community. "We would prefer that the Iranian regime follow through on their offer to engage," said Ellen Tauscher, the US undersecretary of state for arms control and international security. "It is more important for them to build confidence with the international community," she said at a news conference Sunday at the Halifax International Security Forum in Nova Scotia.