The Yugoslav People's Army (JNA/ЈНА), also called the Yugoslav National Army, was the military of the Socialist Federal Republic of Yugoslavia and its antecedents from its founding in 1945 to its breakup in 1992. The branches consisted of the Ground Forces, Navy, Air Force and Territorial Defense.

The President of the Republic acted as commander-in-chief of the armed forces, while administration and defence policy was carried out by the Government through the Ministry of Defence. The highest operational authority, in charge of the deployment and preparation of the armed forces in peace and war, was the General Staff. Military service was compulsory for all men.

Following the disintegration of the state, the JNA ceased to exist in 1992 amidst the conflicts of the Yugoslav Wars, and the units stationed in their respective republics formed their owned respective armed forces, while the remnants of the JNA in Serbia and Montenegro, became part of the new Yugoslav Army.

The military was formed in March 1945 as the Yugoslav Army on the organizational framework of the People's Liberation Army of Yugoslavia (NOVJ), the anti-fascist resistance movement which liberated the country from the Axis powers during World War II in Yugoslavia. It was renamed Yugoslav People's Army on 22 December 1951, the tenth anniversary of the 1st Proletarian Brigade's establishment. This date was officially celebrated as the "Day of the Army" in the Federal People's/Socialist Federal Republic of Yugoslavia (FPR / SFR Yugoslavia).

The support the Soviets had within JNA ranks during the Informbiro period, after 1948, is contested. Low-end estimates indicate that 10–15% of the army's personnel favoured the Soviet position. Yugoslav sources estimate the number of military members arrested ranged from 4,153 officers and soldiers (estimated by Radonjić), to 7,000 imprisoned officers estimated by Milovan Đilas. The purge included 22 officers in the presidential guard regiment reporting directly to Josip Broz Tito, including Momčilo Đurić, wartime commander of the Yugoslav Partisan Supreme Headquarters escort battalion. During this period of Soviet blockade, the Yugoslav Army's development stagnated.

Forty-nine Yugoslav Army graduates of the General Staff Academy, the Frunze Academy, and other Soviet military academies were deemed potential Soviet supporters. Many of those attending such academies in the USSR at the time of the Tito–Stalin split never returned to Yugoslavia.

The split particularly affected the Air Force. Almost all Air Force officers had Soviet training, and some of them fled Yugoslavia in Air Force planes. The defectors included Major General Pero Popivoda, who was the head of the Air Force operational service. The Batajnica, Zemun, and Pančevo airbases near Belgrade saw several attacks by groups of saboteurs. The Zemun airbase commander and his deputy fled to Romania.

Between 1948 and 1955, the United States gave Yugoslavia US$600 million in direct military grants and an equal amount in economic aid, enabling Yugoslavia to devote more of its domestic resources to defence. After two visits to the United States by Colonel General Koča Popović and Colonel General Milo Kilibarda in May–June and August 1951, respectively, U.S. weaponry began arriving by late 1951. By 1952 the Armed Forces had grown to 500,000 troops, and defence expenditures consumed 22 percent of the gross national product. A Military Assistance Advisory Group (MAAG) of 30 officers commanded by Brigadier General John W. Harmony was established by the United States in Belgrade in 1951. It operated for ten years, disbursing military grants and arranging another US$1 billion in arms sales on favorable terms. Among weapons transferred were 599 M-4A3 tanks, 319 M-47 tanks, 715 M-7, M-18, and M-36 self-propelled guns, 565 M-3A1 and M-8 armored cars, and a total of 760 105mm, 155mm, and 203mm artillery pieces. The artillery pieces delivered were used to reequip artillery units within Yugoslavia's eight divisions.