Iranian President Hassan Rouhani said on Tuesday that the United States does not dare to attack Iran as it is aware of the Islamic Republic's military power and the high price of conflict.
"Why the United States does not attack us? Because of our power, because it knows ...its consequences," Rouhani said in a speech broadcast live on state television.
Rouhani also said the country had to develop its military forces to prevent other states taking over its territory and resources.
"We should make ourselves ready to fight against the military powers who want to take over our territory and our resources."
Iran unveiled its first domestic fighter jet at a defense show in Tehran on Tuesday.
Images on state television showed Rouhani sitting in the cockpit of the new "Kowsar" plane at the National Defence Industry exhibition.
It is a fourth-generation fighter, with "advanced avionics" and multi-purpose radar, the Tasnim news agency said, adding that it was "100-percent indigenously made".
State TV said the plane had already been through successful testing and showed it waiting on a runway for its first public display flight.
The plane was first publicly announced on Saturday by Defense Minister Amir Hatami, who had said it would be unveiled on Wednesday.
He gave few details of the project, focusing instead on Iran's efforts to upgrade its missile defenses.
Hatami said the defense program was motivated by memories of the missile attacks Iran suffered during its eight-year war with Iraq in the 1980s, and by repeated threats from Israel and the United States that "all options are on the table" in dealing with the Islamic republic.
"We have learned in the (Iran-Iraq) war that we cannot rely on anyone but ourselves. Our resources are limited and we are committed to establishing security at a minimum cost," he said in a televised interview.
The US has sold hundreds of billions of dollars of weapons to Iran's regional rivals, but has demanded that Tehran curb its defense programmes, and is in the process of reimposing crippling sanctions in a bid to force its capitulation.