At the same time Japan’s interference with the interests of the Western
powers in China became much more direct, and created serious friction.
Difficulties were most acute at Tientsin, Shanghai and Amoy. The
Japanese army imposed various restrictions. It kept Western shipping
off the Yangtze River above Shanghai, and the Pearl River below Canton.
Western traders had to face many practices--tariffs, exchange controls,
import and export controls--which were put into effect especially to
hamper their trade. The Japanese enforced a blockade of the British
and French Concessions at Tientsin, and stripped British citizens for
examination before allowing them to enter or leave their Concession.
Although the Western powers resented these Japanese actions, they
limited their opposition mainly to protests. In July 1939 the United
States abrogated its trade treaty with Japan, but did not follow up
this step by imposing trade penalties.