TOKYO - Hassan Rouhani arrives on the first visit by an Iranian president to Japan in 19 years, just as the US strengthens enforcement of its sanctions in a standoff over nuclear development.

Japan, which is walking a tightrope between its tradition of friendly ties with Iran and reliance on the US as a military ally, is keeping the visit low key. Formerly one of Iran's biggest customers, Japan hasn't imported any oil from the country since May, according to government and ship-tracking data.

US President Donald Trump's administration is seeking to step up enforcement of Iran sanctions by increasing pressure on global shippers, Chinese state-owned enterprises and exporters of raw materials used in metals production, US officials told Bloomberg this week.

Since Mr Trump withdrew from the Iran nuclear deal in 2018, Tehran refused to buckle to American demands for a more comprehensive agreement and has moved forward with efforts to enrich uranium. Japanese Prime Minister Shinzo Abe has tried to ease tensions, including by making the first visit to Iran by a sitting Japanese premier in 40 years.

Mr Rouhani is set to meet with Mr Abe, but the two leaders will not give a joint press conference, and he is scheduled to leave the country in less than 24 hours.(FA)