Mikoyan-Gurevich MiG-19, Hungarian and Romanian users

The Mikoyan-Gurevich MiG-19 was the first supersonic fighter in the world. The "P" variant was equipped with the RP-1 Izumrud radar in the nose and was armed with two 23 mm NR-23 (with some revised versions having them replaced by the 30 mm NR-30) placed in the wings. It could carry some unguided missiles in hardpoints at  the wings and, in further modifications, it could carry also K-13 air-to-air missiles.
The PM variant was not armed with cannons at all, but it was armed with four Kaliningrad K-5M beam-riding air-to-air missiles, making it a pure interceptor.
These two variants were employed by both Hungary and Romania:

• Hungary: The Air Force of the Hungarian People's Army operated 12 MiG-19PM fighters. The first 12 pilots for these aircraft started their conversion training in the USSR in July 1959. In March 1960 six aircraft were delivered with the other six being delivered in April. They were assigned to the 3rd Squadron of the 31st Fighter Regiment based at Taszár Air Base, in Hungary.
  They served until 1974 when the last MiG-19PM was written off and the surviving aircraft were placed into reserve at a disposal dump site where they received fake four digit serials matching the years they were put into storage. Therefore it wasn't uncommon to see various aircraft sharing the same serial number. 
• Romania: In 1959 the Air Force of the People's Republic of Romania received 10 MiG-19P and 45 MiG-19PMs and five more MiG-19P arrived one year later. They were assigned to the 66th Fighter Division which was tasked with the aerial defence of Bucharest.
  Initially they were based at Caracal-Deveselul Air Base but in the early 1960s they were moved to Borcea Air Base (which is still active nowadays) with a detachment assigned to Giarmata Air Base, near Timisoara, in Transylvania. Due to security reasons the fighters were re-serialised twice through their career. They were phased out in the early 1970s, although some reports claim they served a little bit longer, until the mid 1970s.
  There have also been false reports about Romanian MiG-19S fighters, but they were proven wrong.

Sources:

1. https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-19#Variants

2. Midland Publishing - Mikoyan-Gurevich MiG-19. The Soviet Union's First Production Supersonic Fighter

3. Salamander Books - The Complete Book of Fighters

Mikoyan-Gurevich MiG-17F, part five, Romanian and Soviet users

The Mikoyan-Gurevich MiG-17F was also used by every Warsaw Pact country member. Among them Romania and the USSR, as expected.

• Romania: In 1952 the People's Republic of Romania received a batch of 48 MiG-17Fs which were delivered in three stages with the last one being delivered in 1955. When, in 1958 the first MiG-19s were delivered, they were gradually withdrawn from active fighter service and sent to ground support duties, although they were technically never used in combat. During the 1960s some of them were still active and they were kept in active service with the Romanian Air Force until as late as 1992 when they were written off.
• USSR: The MiG-17F was designed for interception of enemy bombers, and not for dog fighting. As it's a subsonic fighter, it was effective against slower (0.6-0.8 mach) heavily loaded American fighters, as well as the main American bombers during its development period in the early 1950s like the piston-powered B-50 Superfortress or the Convair B-36 Peacemaker which was mixed jet and piston-powered. The MiG-17F (which composed the bulk of every Soviet Air Arm during the early-to-mid 1950s) wasn't however able of intercepting the newer generation of bombers that appeared in the mid-1950s like the Avro Vulcan or the Handley-Page Victor as they could flight higher. As the USAF introduced strategic bombers capable of supersonic dashes like the Convair B-58 Hustler or the General-Dynamics FB-111 in the early 1960s, the MiG-17 was rendered obsolete for front-line PVO (Soviet Air Defence Forces) service and they were replaced in that service branch by the MiG-21 and MiG-23.
  In 1958 PVO's MiG-17Fs shot down an American reconnaissance Lockheed C-130 Hercules that was flying over Armenia causing 17 casualties and, during the Prague spring in 1968, the Soviet Forces destined there, used MiG-17Fs to flight over Czechoslovakia.

Sources:

1. https://en.wikipedia.org/wiki/Mikoyan-Gurevich_MiG-17#Operators

2. https://en.wikipedia.org/wiki/Soviet_Air_Defence_Forces

3. https://en.wikipedia.org/wiki/Romanian_Air_Force

4. http://www.aeroflight.co.uk/tag/romanian-air-force

5. Salamander Books - The Complete Book of Fighters

Aero L-29, part four, various European users users

As we've previously said many time, the Aero L-29 was used by many Eastern bloc countries. The ones covered in this post are:

• Hungary: As it happened with almost every other Warsaw Pact country, Hungary bought a number of Aero L-29 in the mid 1960s (in 1965 to be more precise) to equip their training squadrons. They served until the fall of communism in 1989 together with other more advanced and modern types. 
• Romania: Being a Warsaw Pact member, the Romanian Air Force was supplied with a number of Aero L-29 to equip their training squadrons and flight schools. They served until the fall of communism in 1989 and shortly beyond, together with other types.
• Slovakia: After the creation of the Slovak Air Force in 1993, there were many L-29s left in the country which served as the main trainer for the newly created air force. It served alongside the more advanced Aero L-39 until the very late 1990s when it was phased out.
• USSR: The Soviet Air Force (VVS) was the main user of the Aero L-29. It served as its main trainer, together with other types until the dissolution of the USSR in 1992.

Sources:

1. https://en.wikipedia.org/wiki/Aero_L-29_Delfín

2. https://en.wikipedia.org/wiki/Hungarian_Air_Force

3. https://en.wikipedia.org/wiki/Romanian_Air_Force

4. https://en.wikipedia.org/wiki/Slovak_Air_Force

5. https://en.wikipedia.org/wiki/Soviet_Air_Forces