The Philippines and Vietnam are encouraging the United States to follow through with plans to have American aircraft and warships regularly challenge parts of the South China Sea that China claims to control. While there is some risk (of escalation and violent encounters) it has long been American policy to actively oppose such claims. For example in 2014 the U.S. sent aircraft and warships to challenge 19 such claims by six countries (China, Iran, Philippines, Argentina, Brazil and Venezuela). China gets most of the media coverage in this area but China is not the only one doing it. This has been such a widespread and persistent problem that, once the Cold War ended in 1991, there was finally an opportunity to get this all sorted out and an international treaty was agreed on and signed by the most nations to deal with the endless disputes in this area and all of the resulting harassment of ships and aircraft in international waters. The new treaty (the 1994 Law of the Sea treaty) recognizes the waters 22 kilometers from land as under the jurisdiction of the nation controlling the nearest land. That means ships cannot enter these "territorial waters" without permission. More importantly the waters 360 kilometers from land are considered the Exclusive Economic Zone (EEZ) of the nation controlling the nearest land. The EEZ owner can control who fishes there and extracts natural resources (mostly oil and gas) from the ocean floor. But the EEZ owner cannot prohibit free passage or the laying of pipelines and communications cables.
While the new agreements eliminated or reduced many of the existing or potential disputes it did not completely eliminate them. Thus some nations keep violating the agreements, usually because they feel their claims supersede the international agreements. China is the most frequent abuser of the 1994 treaty, which it signed. For example China claims that American electronic monitoring ships are conducting illegal espionage while in the Chinese EEZ. But the 1994 treaty says nothing about such matters. China is simply doing what China has been doing for centuries, trying to impose its will on neighbors, or anyone venturing into what China considers areas under its control. China is not alone, but because China is pushing the limits of how the 1994 law can be interpreted (or misinterpreted) other nations with similar opportunities to lay claim to crucial chunks of the seascape are ready to emulate China if some of the more aggressive Chinese ploys actually work.
Both the Philippines and Vietnam have encountered forceful even violent and sometimes deadly resistance from the Chinese in the past. Both countries believe the Chinese would not dare use those tactics against the United States. Currently Filipino fishermen are complaining that Chinese Coast Guard crews are robbing Filipino fishing boats that are accused of being “illegally” in Chinese waters near disputed areas like Scarborough Shoal. This area is 220 kilometers from one of the main Filipino islands (Palawan) and 650 kilometers from Chinese territory (Hainan Island). The Chinese coast guard has a reputation for theft and other illegal activity. The Chinese government has cracked down on the worst examples of that (like assisting in the hijacking of ships or aiding smugglers) but it is known that the thefts still occur, especially when they involve non-Chinese boats.
May 16, 2015: In the south (Basilan) an army raid on the home of a known Abu Sayyaf leader led to a firefight that left three Islamic terrorists and a soldier dead. The troops found bomb making components in the house. Nearby troops found twenty assembled bombs that were hidden for later use.
May 15, 2015: In the central Philippines (Samar) two off-duty soldiers were killed and one wounded during an NPA ambush.
May 11, 2015: A Philippines general (the head of the armed forces) visited Thitu Island, which is only 37 square kilometers of low-lying ground and 480 kilometers from the closest large Filipino island (Parawan). Thitu is the second largest of the Spratly Islands, which China claims. The Philippines has occupied the island since the 1970s and currently 200 Filipino civilians and fifty military personnel live there. The military base has an airstrip. From Thitu you can see China building an artificial island on Subi Reef, which is 24 kilometers away.
May 10, 2015: In the south (Basilan) soldiers, with the help of local volunteers, drove Abu Sayyaf gunmen from a police guard post the Islamic terrorists had seized on May 2nd. The guard post was near a cell phone tower where the Islamic terrorists planted a bomb. Troops and bomb experts came and disabled that bomb and moved on. It was left to the locals to organize an effort to chase the armed Abu Sayyaf men from the area.
May 9, 2015: In the south (Davao Occidental province) four soldiers were killed and eight wounded when they clashed with a large group of NPA rebels who had been extorting food and cash from rural villagers (who had quietly called on the army to help them out). The leftist rebels fled with their dead and wounded. Elsewhere in the south (Maguindanao) three soldiers were wounded when hit by a roadside bomb planted by BIFF (renegade MILF) rebels.
May 5, 2015: In the south (Sulu) quick response by bodyguards, police and local defense volunteers thwarted an Abu Sayyaf attempt to kidnap (for ransom) a local businesswoman. In a series of clashes that went on for two days five of the Islamic terrorists were killed and the victim wounded.
May 3, 2015: A much wanted Islamic terrorist bomb maker, Abdul Basit Usman, was killed in a gun battle between his bodyguards. Some of the bodyguards attempted to take Usman and turn him in for the million dollar reward but were apparently killed by loyal bodyguards in a fierce gun battle that left no unwounded survivors. MILF later found the bodies and soon MILF announced that they had killed Usman while trying to arrest him. But witnesses soon came forward to reveal what really happened. This all began in March when years of pressure from the government finally forced MILF to agree to hand over Abdul Basit Usman, who had enjoyed protection from one MILF faction or another for over a decade. MILF ordered their men to arrest Usman if they encountered him. Usman and his bodyguards got tipped off and got away. Usman survived for so long by becoming a freelance bomb builder. He produced bombs for anyone who would pay and provided training on how best to place and activate the bombs. His best paying customers were not Islamic terrorists but local gangs, politicians and businessmen who all used bombs to eliminate or intimidate rivals or extortion targets. Government bomb experts had suspected this was going on because they found many of the bombs going off in the south were apparently made using the same designs and were probably made by one very skilled bomb designer. Usman got started working with Islamic terrorists in Indonesia but a crackdown there saw him flee back to the Philippines where his presence was noted in 2007. At that time the U.S. has offered a $50,000 reward for the capture of Usman. Over the years the size of that reward has escalated.
April 23, 2015: The Philippines accused China of threatening an unarmed Filipino patrol aircraft when it recently flew over disputed Subi Reef. A Chinese warship focused a powerful light on the aircraft and radioed the Filipino pilots to stay away or else. China denied any threats but remarked that the Filipino aircraft should not have been there.
April 21, 2015: American and Filipino forces began their annual joint military exercises. This year 12,000 personnel were involved, twice as many as last year. China condemned the exercises as an illegal provocation while Filipino officials pointed out that these exercises should remind China that bullying the Philippines over illegal Chinese territorial claims involves more than just China and the Philippines.