The journey to Tehran from the border with Iraq was a long one. But Alex successfully made his way to the country in as covert as a manner as possible. Of course, there were spies inside the Iranian nation that worked on behalf of its enemies.
Enemies, who Alex had in common with the Iranians, but these spies did not manage to identify Alex, or his purpose for visiting the nation. Eventually, Alex was brought into a holding area, no doubt to be interrogated by Iranian intelligence.
After all, when a foreigner shows up at your borders, stating they wish to help you with a nuclear weapons project, something which the rest of the world condemned. It would naturally arouse suspicion. And because of this, Alex sat in a room waiting for the interrogator to arrive.