The Shanghai Port has sealed off entry for US and Japanese ships, effective immediately. The move is part of efforts by the Chinese government to protect its ports from potential threats. The decision was made after security experts identified suspicious activity on the port's surveillance cameras. The Chinese government has been working with other countries to monitor the movement of shipping traffic through the Yangtze River. This includes using technology such as drones and radar systems to track vessels and detect any potential threats. The move comes at a time when China is facing increasing international pressure to improve security measures along its borders. The Shanghai Port has been in the forefront of this effort, and it is expected that the closure of entry will help prevent any potential risks to the country's trade and commerce.