Washington doesn't take a formal position on sovereignty claims in the area but regards the South China Sea largely as global waters in which its navy has the right to operate within legal confines.
The size of the Chinese Navy force is unusually large and is meant to show off China's naval power in contested waters.
"We have seen Chinese ships around us", Rear Admiral Steve Koehler, the strike group commander, told a small group of reporters on board the three-decade-old carrier.
There is nothing inappropriate with China stationing troops and deploying territory defense facilities in the disputed South China Sea as it is the country's natural right, Senior Colonel Ren Guoqiang, spokesperson for China's Ministry of National Defense (MND) said.
The usTheodore Roosevelt's presence inside the South China Sea comes days after China carried out large air and naval drills inside the area - in what some analysts described as an unusually huge present of Beijing's rising naval might.
Navies in the western Pacific, including China and nine Southeast Asian countries, have been working on a code of unexpected encounters (CUES) at sea to avoid conflict.
Beijing has maintained that its military buildup across the South China Sea is strictly for defensive measures.More news: Russian MoD: Two Israeli Warplanes Attacked Syrian Airbase From Lebanon Airspace
More news: Amazon.com, Inc. (AMZN) EPS Estimated At $1.19
More news: Syria Airstrike Warning: Airlines re-routing flights
"What the U.S. is doing will damage the military-to-military relations and atmosphere".
At least twice this year, the U.S. Navy has deployed destroyers in freedom of navigation sail-bys near Chinese-occupied Scarborough Shoal, which Beijing wrestled from the Philippines in 2012, and Manila-claimed Mischief Reef, which Chinese forces occupied in 1995.
"I haven't seen any risky interaction", Koehler said, adding that problems could be avoided "if all the navies are operating in accordance with the global norm and law".
China is creating new vessels in a fast speed to equip its navy, coast guard and marine regulation police agencies, including its first entirely domestically-built aircraft provider.
The Philippine ambassador to Beijing, Chito Sta.
American officials have said U.S. Navy ships will continue sailing close to Chinese-occupied areas without prior notice, placing Washington in a continuing collision course with China's interests.
"Since Americans are our friends in one way or another, they can help us deter any threat".