China has been rapidly reclaiming land and making artificial islands in the South China Sea during the past year, causing strong reaction in the U.S. and many other countries.

Senator John McCain, chairman of the U.S. Senate Armed Services Committee, said island building is just the beginning.

McCain said the next step for China will be to militarize those islands and declare an Air Defense Identification Zone (ADIZ) over the South China Sea to further its sovereignty claims.

"They build runways; they are going to put weapons there, and the next thing you will see the Chinese do is when an American aircraft [flies by], whether being a commercial craft or what, they will say 'identify yourself' – establishing an Air Defense Identification Zone, which then means territorial sovereignty," McCain said last week at the Hudson Institute, a Washington-based think tank