Behnaz Hekmati and her husband, Ali Hekmati, talk in 2013 about their son, former U.S. Marine Amir Hekmati, who is being detained in Iran accused of being a CIA spy. (Ryan Garza/Detroit Free Press via Associated Press)

WE’VE ARGUED that the unjust arrest, secret trial and prolonged imprisonment in Iran of The Post’s Jason Rezaian raises the question of whether any Western company considering investment in the country can safely dispatch its personnel there. Now the danger has been underlined. In recent days the arrests of two businessmen visiting Iran — both with connections to the United States — have come to light. Nizar Zakka, a Lebanese information technology specialist and permanent U.S. resident, disappeared on Sept. 18 while attending a government-sponsored conference in Tehran. About a month later, Siamak Namazi, a Dubai-based oil industry consultant with dual U.S. and Iranian citizenship, was arrested while visiting a friend in Tehran.

That makes four Iranian Americans imprisoned by the regime, plus Mr. Zakka; a fifth American, retired FBI agent Robert Levinson, has been missing since disappearing on a 2007 trip to the country. None has been shown to be guilty of any crime — much less the extravagant and ridiculous charges of espionage that, in the case of Mr. Rezaian, have been reported in the Iranian media. On Tuesday, Iranian television broadcast a photograph of Mr. Zakka in uniform to back up its claim that he worked for U.S. military and intelligence agencies. It turned out the photo came from a reunion at his military high school in Georgia.

Mssrs. Zakka and Namazi reportedly were seized by the intelligence service of the Iranian Revolutionary Guard Corps (IRGC), the state-within-a-state that operates beyond the control of the government of President Hassan Rouhani. Mr. Rouhani is hoping to revive Iran’s economy with Western investment in the wake of the recently concluded deal on Iran’s nuclear program. But that opening would threaten the ideological principles — and, more importantly, the corrupt business interests — of the IRGC leadership.

The Wall Street Journal reported that Iranian businessmen associated with foreign companies had recently been detained and warned not to infringe on the monopolies enjoyed by the scores of companies controlled by the IRGC. That also could explain the arrests of the two businessmen. Mr. Namazi, a veteran of the Iranian oil business, has been a public advocate of improved relations between Iran and the West, while Mr. Zakka, who was based in Washington, was affiliated with a company that promotes Internet development around the Middle East.

President Obama has frequently suggested that the nuclear deal would prompt a relaxation of barriers between Iran and the West. So far, the opposite appears to be happening. While anticipating the collection of up to $100 billion in frozen assets, Iran’s military and security services are acting to ensure that there is no further detente. In that they have the support of Supreme Leader Ayatollah Ali Khamenei, who on Tuesday celebrated the anniversary of the seizing of hostages at the U.S. Embassy by proclaiming that the slogan “death to America” will live forever.

The Obama administration has reacted to these provocations, including the new arrests, with the equivalent of a shrug. When asked about them, a State Department spokeswoman said, “This is something that we continue to have dialogue on.” Republicans, including House Foreign Relations Committee Chairman Edward R. Royce (Calif.), have proposed imposing new sanctions on the IRGC. If the Americans are not soon released, that would be a logical course.