This aerial photo taken through a glass window of a military plane shows China's alleged on-going reclamation of Mischief Reef in the Spratly Islands in the South China Sea Monday, May 11, 2015.

This aerial photo taken through a glass window of a military plane shows China's alleged on-going reclamation of Mischief Reef in the Spratly Islands in the South China Sea Monday, May 11, 2015. Ritchie B. Tongo/Pool Photo via AP

Navy Unveils Video of Manmade Islands in South China Sea

Defying Chinese orders to get lost, a Navy P-8 patrol plane flew over the reefs Beijing is turning into full-fledged footholds.

The Pentagon has released video, taken high above the South China Sea, of Chinese construction crews expanding reefs and building an airbase in the contested Spratly Islands.

The video shows dozens of ships surrounding the reefs, which are being enlarged as part of China’s efforts to declare sovereignty over the disputed region. One of the islands has the clear outline of a runway under construction.

The Pentagon characterizes the flight as a “maritime domain awareness” mission, said spokesman Col. Steven Warren.

“We have for some time, and will continue to conduct freedom-of-navigation operations in the South China Sea,” Warren said.

The Pentagon says flights like this are routine and that the U.S. Navy planes flying them stay in international airspace, never passing directly over the islands.

“We’re going to continue to operate thoughout the South China Sea and around the world consistent with international protocols and laws and customs,” Warren said.

The video released Thursday was taken from a Navy P-8, a militarized Boeing 737 airliner. The jet resembles a commercial Southwest Airlines plane on the outside, but its insides are far more sophisticated.

The Poseidon , as it’s called, is outfitted with computer workstations connected to the jet’s advanced radar, sensors and communications gear. The plane can also carry torpedoes, missiles and bombs under its wings or inside a weapons bay in the aircraft’s belly.

At several times throughout the flight, the People's Liberation Army Navy warned the P-8 to leave the area. It did not.

The U.S. Navy late Thursday released audio of radio calls ordering the P-8 to go away as it neared the islands. In the nearly nine-minute clip, there are numerous back-and-forth transmissions between the P-8 crew and the voices claiming to be the Chinese navy.

“Foreign military aircraft, this is Chinese navy,” the voice said. “You are approaching our military alert zone. Leave immediately in order to avoid misjudgment.”

At another point, one of the voices tells the P-8 crew “your actions are dangerous.”

The P-8 crew responds the same way each time. “I am a United States military aircraft conducting lawful military activities outside national airspace. I am operating with due regard, as required under international law.”

CNN had requested to fly on one of these missions, according to Pentagon officials. The Navy brought along a videographer to also capture the video that was publically released Thursday. CNN aired its own video on Wednesday night.

The P-8 that captured the video was part of Patrol Squadron 45, a unit based out of Okinawa, Japan. The specific mission over the Spratly Islands originated from Clark Air Base in the Philippines.

Parts of the Spratly Islands are claimed by China, Taiwan, Brunei, Vietnam, Malaysia and the Philippines.