Prime Minister Shinzo Abe has dropped his plan to visit Iran this summer, government sources said Tuesday, as U.S. President Donald Trump has taken an increasingly tough line against Tehran.

The government was making arrangements for Abe to visit the Iranian capital in mid-July and hold talks with President Hassan Rouhani. The trip would have made Abe the first Japanese leader to visit the country since Takeo Fukuda in 1978.

But the sources said the government told the Iranian side by late June that Abe would not be able to make the trip.