The United States is sending warships to parts of the South China Sea claimed by China and will continue to do so, U.S. Admiral Harry Harris Jr. said on Tuesday.
After a U.S. warship last week sailed by an artificial island made by the Chinese, China said the U.S. was trying to "militarize" the region. America, however, says the patrol is just an exercise in the "freedom of navigation."
So what's going on?
What's at stake in the South China Sea?
China wants control of the Spratly Islands and the area around it in the South China Sea because they want to control shipping lanes and resources in the region. Those resources include vast fisheries and possible large oil and gas fields. Ships from all over the world also send $5 trillion in trade through the region every year.
The U.S. wants China to stop claiming islands in the South China Sea in part because America ships around $1.2 trillion in trade through the region each year.
Why is this an issue now?
The USS Lassen sailed within 12 nautical miles of a Chinese man-made island near the Spratley Islands in the South China Sea on Oct. 27. China says it controls the waters up to 12 nautical miles around those islands, though the U.S. and other nations don't recognize those claims.
Chinese ships followed the USS Lassen but did not get in its way. Officials in China said the U.S. was unnecessarily flexing its muscles, but U.S. officials said the patrol was just like missions the navy conducts around the globe.
Why is the U.S. patrolling the South China Sea?
China has built artificial islands in the South China Sea over the past two years to support their territorial claims. Those islands are equipped with basic military structures, ports and airstrips.
The U.S. says it is concerned that China is taking over international water. America also supports other nations that claim parts of the region, such as the Philippines.
Who else has interests in the South China Sea?
Taiwan and the Philippines claim large parts of the Spratly Islands, while Malaysia and Brunei believe they own a few of the islands in the south.
Vietnam says it has documents to prove it has owned the Spratly Islands and the northern Paracel Islands for centuries. China stormed the Paracels in 1974, killing 70 Vietnamese soldiers and taking the islands.