The US was targeting Japan when passing the Export Control Act of 1940. This law was passed in order to limit the Japanese Empire from getting certain resources that could help make planes, chemicals, and minerals that could be used for weapons. The US feared these materials getting into the hands of the Japanese because they were worried about the way in which they used them.
Since the US was supporting the Allied Powers (the enemies of the Japanese) through the Lend-Lease Act, it would go against their views.
