The Chinese Navy issued eight warnings this week to a US surveillance aircraft sent into a region of the South China Sea, where China has been conducting mass land reclamation in the disputed region.

"This is the Chinese navy, this is the Chinese navy, please go away quickly," said the recorded radio transmissions between the Chinese navy and a US spy plane, which were declassified by the US Navy and released Thursday evening.

The incident occurred on Wednesday, May 20 when a P-8A Poseidon aircraft was flying over the South China Sea.

"I am a United States military aircraft conducting lawful military activities outside national airspace," responded crew members aboard the US aircraft. "I am operating with due regard, as required under international law."

Later, an increasingly urgent Chinese radio operator responded, "you are approaching our military alert zone," and adds, "your action is dangerous."

The US Navy also released footage of land reclamation shot during the recent flights. Pentagon officials have said China has reclaimed some 2,000 acres of land in the South China Sea, creating a string of artificial islands to strengthen its territorial claim over the area. China's claims are disputed by the Philippines, Brunei, Malaysia, Vietnam, and Taiwan.

CNN was given access to board surveillance flights over the South China Sea by the Pentagon. According to the network's report, this was, "in order to raise awareness about the challenge posed by the islands and the growing US response."

Captain Mike Parker, commander of the surveillance aircraft being used in the region, told CNN while aboard the P8 flight that he believed the Chinese radio commands came from Fiery Cross Reef, one of the biggest artificial islands created by Chinese land reclamation.

"The challenge came from the Chinese navy, and I'm highly confident it came from ashore, this facility here," he said, gesturing to a radar facility on the reef.

The flights follow reports last week that the Pentagon is considering the deployment of ships and aircraft within 12 miles of Chinese installations. The 12-mile zone around a country's claimed landmass is generally accepted as being that country's territorial waters. By deploying within those 12 miles, the US would be demonstrating disregard for China's territorial claims.

This potential deployment has some analysts concerned about the possibility of a confrontation between China and the US. Professor Sam Bateman, a former Commodore in the Australian Navy, told VICE News the possibility of an accidental engagement was growing with the militarization of the region.

"Putting more war ships and more aircraft into disputed waters is unreasonably provocative and increases the risks," he said. "The objective of all parties should be to demilitarize the region under dispute rather than ramping up militarization."

"Air encounters are very hard to manage, and the most likely thing is an encounter going wrong, like the Hainan incident," he said, referring to the 2001 occurrence that caused uproar when a US spy plane collided in mid air with a Chinese navy aircraft. The US aircraft was forced to land in China, where the crew was briefly held and the plane's computer systems ransacked.

The US and China have negotiated protocols for what they call "unexpected encounters" to minimize the chance of anyone accidentally shooting at the other in an engagement. Bateman noted that while protocols have been agreed for naval disputes, the two sides still have no agreement on instances of air-to-air encounters, leaving a worrying black hole in policy. The two countries have committed to agreeing on a protocol by the end of the year.

"There are 101 things countries operating in the region could be doing to reduce the risks that we're not seeing at present," he said, citing as priorities emergency hotlines between commanders and sharing information on flight paths and locations of ships to avoid confusion.

Follow Scott Mitchell on Twitter: @s_mitchell