Optimism prevailed when United Nations sanctions against Iran were lifted in mid-January. Since the historic nuclear deal was reached last July between Iran and six global powers, companies, including those in Japan, had been vying for economic opportunities in a Middle Eastern market rich in natural resources.

But Japanese firms are still taking a wait-and-see approach because U.S. restrictions remain against financing businesses in Iran.

The nuclear deal laid the groundwork for global investment in the economically challenged country. It gives Tehran access to its frozen assets, and the country can now engage in oil and gas sales, which would bring foreign capital.