Your version of the Philippines' history is laughably wrong. We gained ownership of the islands around the turn of the century, not by the war as you imply. It's true that despite initially supporting the Philippines independence movement from Spain, we waged our own war against a rebelling populace after we received the islands in the Treaty of Manila (ending the Spanish-American War). The destroyed infrastructure was of the same pre-Industrial-Revolution kind that was largely being willfully destroyed elsewhere in the world. In the interrim, the Philippines prospered alongside the US - we established a modern health care system rivaling our own at the time, ended slavery, formed a national education system and civil bureaucracy. Throughout the 1930s efforts toward releasing the Philippines as a free and independent nation were well underway, with the first independent government elected in 1935 and the transition to be gradual to full independence a decade later.
In WWII, the Japanese conquered the Philippines despite American and Phillipine attempts to defend it. Philippine and US troops alike died in the Bataan Death March. We of course hosted the legitimate citizen-elected government as a government-in-exile. After the official withdrawal of US troops, the Philippine Army )with large participation from underground movements) waged a guerilla war with support from what US remnants remained - against the unpopular Japanese-puppet regime. When we reinvaded in 1944, the civilian president Osmena literally accompanied MacArthur onto Leyte Island.
We ceded the Philipines as scheduled before the war, in July 1946 - a mere 10 months (nearly to the day) after Japan's formal surrender.
You paint a picture of an invading US army laying waste to the country and then holding onto it during and after WWII, when the exact opposite is far closer to the truth.
As a former Filipino (a national of the Philippines is called that instead of Philippino), I could be considered an expert here. I was also born in Mindanao but I am a Christian. I also consider myself a history buff. Philippine history was mostly told from the eyes of the west who colonized it - both Spain and the USA. The acquisition of the Philippines by USA from Spain was a result of the Spanish-American war because the US supported the Cuban war for independence, for doing so, Spain was also at war with the USA. At the same time, Filipino (for lack of a better term, the country was not yet established then) freedom fighters were trying to gain independence from Spain but for the Spanish government to save face (they were for all intents defeated by the Filipino rebels), they surrendered to Adm. Dewey who was sent there by the US govt. to wage war against Spain. Spain ceded the Philippines in the 1898 Treaty of Paris and they (Adm. Dewey and Spanish Gov. General of Philippines Jaudenes) staged a mock naval battle in Manila Bay thus setting the stage for the surrender to Adm. Dewey. The Filipino fighters felt betrayed because they thought they had won the revolution but now had to contend with another master to govern them.
The revolutionaries then fought a war against the American forces who were superior in weapons and training. It took a while but eventually they were subdued but at a large cost on the number of dead people. Look at "Balangiga bells" as an example. Also look at the reason and history why the cal.
In the 70s and 80s, the Moro National Liberation Front (MNLF) was established by Nur Misuari, a college lecturer of the premier University of the Philippines. They wanted independence/autonomy from the Philippines. Since Misuari is a Tausug muslim, the Maranao and Maguindanao muslims were wary of his motives and power. They established the MILF. While the MNLF signed a peace treaty with the Philippine government in 1987, the MILF did not do so until 10 years later. Because many felt betrayed and because they had no means of livelihood, another group, the Abu Sayyaf was created. They mostly do kidnappings, assassinations, extortion, and terrorist acts until today. To be credible, they tied up with other international terrorist organizations like Jeemah Islamiyah. I have many muslim friends and some of them even claim that they know MNLF and MILF fighters who were also in Afghanistan helping the Mujaheedin against the Russian occupation.
If you thought that the Philippines is an independent country, a lot of its socio-economic infrastucture is tied to the US. Thus the US government holds sway to a lot of the policies of the government there. Its a free country but its not really free. Most of the conflict is really due to economic reasons but some could ideological. However, give a man a real livelihood where he earns his keep through honest means and he will lay down his arms and live peacefully.