China appears to be building a third airstrip in contested territory in the South China Sea,

 (Territorial disputes in the South China Sea involve both island and maritime claims among several sovereign states within the region, namely Brunei, thePeople's Republic of China, the Republic of China (Taiwan), Malaysia,the Philippines , and Vietnam. ) citing satellite photographs taken last week it has been confirmed.

The photographs taken for Washington's Center for Strategic and International Studies (CSIS) think tank on Sept. 8 show construction on Mischief Reef, one of several artificial islands China has created in the Spratly archipelago.The images show a rectangular area with a retaining wall, 3,000 meters long, matching similar work by China on two other reefs, Subi and Fiery Cross, said Greg Poling, director of CSIS's Asia Maritime Transparency Initiative (AMTI).Security experts say the strip would be long enough to accommodate most Chinese military aircraft, giving Beijing greater reach into the heart of maritime Southeast Asia, where it has competing claims with several countries.

A visit to Washington next week by Chinese President Xi Jinping. U.S. worries about China's increasingly assertive territorial claims are expected to be high on the agenda.

Bill Urban (from US defence), declined to comment specifically on Poling's assessment, but repeated U.S. calls for a halt to land reclamation, construction and militarization of South China Sea outposts to "ease tensions and create space for diplomatic solutions."

If construction work will be continued It is difficult to get diplomatic solution, one of the official from think tank of USA said.

After completion of the airstrip it would allow China to threaten all air traffic over the features it has reclaimed in the South China Sea, he said, adding that it would be especially worrying if China were to install advanced air defenses.

Satellite images from earlier this year showed reclamation work on Subi Reef creating land that could accommodate another airstrip. 

Poling said the latest images made it obvious that such an airstrip was being built at Subi.recent photograph shows China almost completed 3000 mtr long airstrip.

Although a strong criticism from US last year china started doing this activity secretly

Asked about Mischief Reef on Monday, China's Foreign Ministry spokesman Hong Lei repeated China's claim to "indisputable sovereignty" over the Spratly Islands and its right to establish military facilities there.

(Additional reporting by Ben Blanchard in Beijing; Editing by Jonathan Oatis and Christian Plumb)

Beijing must offer more than hollow promises if it wishes to secure peace in the disputed South China Sea and beyond, a spokesman for the Philippine defense department said Sunday.

"The Chinese leadership should go beyond deceitful rhetoric claiming peaceful efforts before their aggression takes a greater and irreparable toll on the region and beyond," Peter Paul Galvez, the department spokesman said in a statement.

"We call on China's government to show its sincerity by, at the least, stopping all ongoing construction and militarisation activities and to refrain from restricting freedom of flight and navigation," in the flashpoint sea, he said.

China claims almost all of the South China Sea -- a vital maritime route, rich fishing ground and potential source of vast minerals -- despite competing claims from the Philippines as well as Brunei, Malaysia, Taiwan and Vietnam.

The Philippines has been the most vocal in criticising China's efforts to enforce its claim by seizing islets and turning isolated outcroppings into artificial islands that can host military facilities.

Galvez added, "the department welcomes the Chinese leadership's recent pronouncement that they are committed to peace, but at the same time china showing their deadly weapons infront of the world.

The Philippines, which has one of the weakest militaries in the region, has been seeking to improve its defense relations with other countries like the United States and Japan to counterbalance China's forces.

The country has also filed a case with an international tribunal challenging China's maritime claim. It seems that China is threat for not only for the south east Asia but it is also a threat for all the world.