The NPA's armed insurrection followed the traditional pattern of guerrilla warfare. NPA units were formed at the regional and front levels and were normally company-sized or smaller. Main regional guerrilla units usually had 80 to 150 fighters, whereas secondary units had 30 to 60 fighters. NPA operations were, by design, extremely decentralized, with local commanders having wide latitude to conduct attacks as they chose. Typically, NPA elements avoided contact with AFP troops by remaining in remote, mountainous areas until ready to stage an attack. For an assault, they concentrated their forces, forming companies and sometimes battalions to overwhelm government troopers. Afterward, they dispersed to avoid AFP retaliation.

Isolated government outposts of the constabulary, police, and militia were favorite targets. The NPA also attacked public buildings such as town halls as a demonstration of its power. The property of uncooperative landowners and businessmen was another common target. The communists normally attacked private property to punish owners for alleged abuses or to coerce the payment of "revolutionary taxes." Attacks on the country's infrastructure were rare the NPA's demolition of several bridges on Luzon's Bicol Peninsula in 1987 created a popular backlash that apparently caused the NPA to abandon the tactic.

The communists' traditionally rural struggle came to the cities in the mid-1980s with the dramatic increase in NPA assassinations. Beginning in 1984, Davao City became the laboratory for the NPA's developing urban warfare strategy. There, armed city partisan units, known popularly as "sparrow teams," murdered local officials, constables, police, and military personnel in a sustained terror campaign. The NPA selectively targeted unpopular officials, claiming that the killings provided revolutionary justice. The NPA's Davao City offensive ended in 1986, but not before Romulo Kintanar, the mastermind of the Davao City offensive and future NPA chief, had initiated a similar operation in Manila. The tempo of sparrow assassinations in the capital increased slowly after 1984, then rose dramatically in 1987. Some 120 officials, including Aquino's secretary of local government, were assassinated by the NPA that year. As sparrow activity escalated, NPA targeting became more indiscriminate.

The guerrillas also targeted Americans in 1987 for the first time since the early 1970s. After threatening to strike official Americans for their support of the Philippine counterinsurgency effort, the NPA killed two United States airmen, an American retiree, and a Filipino outside Clark Air Base in October. In April 1989, NPA assassins struck United States Army Colonel James N. Rowe, a senior officer at the Joint United States Military Advisory Group, on his way to work in Manila. Several other attacks on United States servicemen and contractors followed in 1989 and 1990.

The NPA obtained most weapons from the Philippine military in raids and ambushes. Some guns and ammunition also were purchased locally. As a result, the guerrillas were armed much lik8ba ike the AFP, with an assortment of American-designed small arms, such as the M-16 rifle. NPA commanders complained, however, that weapons shortages hampered their operations. The Philippine military estimated that only one-half to two-thirds of NPA fighters had high-powered rifles. There were no indications in 1990 of foreign-supplied weapons.

Overall, life in the NPA was austere and demanding. Living conditions were harsh, the food generally poor, medical care primitive, and danger constant. The NPA relied on the party's extensive network of peasant supporters in remote villages. The masa (masses) provided food and lodging to mobile guerrilla bands and warned of approaching government troops. The CPP's base also facilitated communication among party and NPA elements through courier, telephone, and telegraph networks. By the late 1980s, NPA communications had become more sophisticated long-range radios were used more frequently. Although women were given equal status as NPA fighters, they were normally given secondary support roles in guerrilla units. Discipline in the NPA was strict, designed to win the support of the people by ensuring that the NPA was not discredited by its members' misbehavior. Punishment under the CPP's system of revolutionary justice ranged from reprimand to expulsion and execution.

Data as of June 1991