Turkey’s President Tayyip Erdogan said on Thursday he wanted the United States to lift recent tariffs on Turkish steel, calling them a big obstacle to increasing trade volumes, Reuters reported.

Washington doubled tariffs on Turkish steel and aluminum in August, when relations between the NATO members were strained by the detention of an American evangelical pastor in Turkey.

Erdogan told U.S. and Turkish businessmen in Ankara that Turkey and the United States should engage in joint investments in defense and space technologies.