The Pentagon has said that five Chinese ships shadowed and maneuvered dangerously close to a US Navy vessel in an apparent attempt to harass the American crew.

Defence officials said that the incident on Sunday followed several days of ‘increasingly aggressive’ acts by Chinese ships in the region. The incident took place in international waters in the South China Sea, about 75 miles south of Hainan Island.

US officials said that a protest was to be delivered to Beijing’s military attache at a Pentagon meeting today.

The USNS Impeccable sprayed one ship with water from fire hoses to force it away. Despite the force of the water, Chinese crew members stripped to their underwear and continued closing within 25 feet,a spokesman for the Defence Department said.

Impeccable crew radioed to tell the Chinese ships that it was leaving the area and requested a safe path to navigate, the Pentagon said. But shortly afterward, two of the Chinese ships stopped directly ahead of the Impeccable, forcing it to an emergency stop to avoid collision because the Chinese had dropped pieces of wood in the water directly in front of Impeccable’s path.

In Beijing, Chinese officials did not immediately respond to voicemail messages and e-mail.