Six months after international sanctions on Iran were lifted following the nuclear deal it struck with major powers last year, Japan should consider more proactive steps to beef up its relations with Tehran, by building on the bilateral investment treaty signed in February to boost economic ties. Prime Minister Shinzo Abe's visit to Tehran has been weighed for months but has yet to take place, reportedly in part due to the lingering sensitivities in the United States over its ties with Iran.

The government should think of closer ties with Iran as Tokyo's contribution to promoting the major Mideast power's return to the international community and supporting the moderate regime of President Hassan Rouhani against domestic hardliners. A possible upset in Iranian politics in its presidential race next year could undermine the nuclear deal and add to instability in the region.

When Japan lifted its sanctions along with others following confirmation by the United Nations nuclear watchdog that Tehran had implemented the steps it promised in the July 2015 accord to curtail its nuclear program, Abe said Japan "must not be left behind" as other countries move quickly to improve relations with Iran, citing traditionally friendly bilateral ties, Iran's rich oil and natural gas reserves and the market potential of the country with nearly 80 million population.