Any armed attack by China on a Philippine ship or plane in the South China Sea, he told the Philippine government, will be treated as an attack on an American ship or plane, bringing a U.S. military response.

"China's island building and military activities in the South China Sea threaten your sovereignty, security and, therefore, economic livelihood, as well as that of the United States," said Pompeo. "As the South China Sea is part of the Pacific, any armed attack on Philippine forces, aircraft or public vessels in the South China Sea will trigger mutual defense obligations under article 4 of our mutual defense treaty."

Article 4 requires the U.S. and the Philippines to come to the defense of the other if one is attacked. The treaty dates back to August 1951. There are Americans on Social Security who were not born when this Cold War treaty was signed.