With the reunification in 1990 the East German Army (NVA = Nationale Volksarmee) was officially disbanded. Their equipment was given to the German government and eventually sold off or given to other countries. Most personell was let go and the few that remained (roughly over 3000 personell) were absorbed into the Bundeswehr and demoted by one rank.

As for the Soviet Forces in the former East German territories, they remained in Germany for a few years after reunification but usually took their equipment back to Russia. It was an interesting day when they left our town, that's for sure.

I have written about the somewhat messy process of reunification and the Bundeswehr here. As the linked answer goes in depth, the Bundeswher's chiefs generally had a low opinion of NVA troops and the Soviet-style, officer-heavy structure of the NVA was ill-suited to the Bundeswehr.

The Bundeswehr chiefs likewise had a very low opinion of the NVA's equipment. Like many of the satellite state armies, the NVA did not receive the best equipment from the Soviets, making the equipment quite superfluous to the Bundeswehr's postWende needs. Moreover, the NVA's equipment often expressed different design philosophies and standards than those in the West. The NVA's T-72s, for example, had both problems with reliability and safety features that while acceptable in an Eastern bloc army, would not really pass muster in the Bundeswehr's armored formations. Likewise, the NVA's Luftstreitkräfte's aircraft were prioritized either for basic tactical missions or for air intercepts guided by ground control. By comparison, the Luftwaffe was a much more sophisticated force and its procurement increasingly prioritized both smart munitions and BVR air defense missions in which pilots had some initiative, but were also tied to AWACs control.

The Bundeswehr assigned three categories for NVA equipment. Category I was equipment used in the short and medium term. Both the MiG-29 and he workhorse Mi-8 helicopter fell in these categories. Category II was a transitional category of equipment that the Bundeswehr judged semi-obsolescent and would be kept on until it could evaluate properly what to do with it. Category III was for that equipment which the Bundeswehr chiefs thought were a drain, and would be disposed of as soon as possible. For the most part, NVA stocks ended up in Categories II and III, with very little ending up in Category I. The Luftwaffe's MiG-29 was the only real piece of ex-NVA equipment that had a significant and prominent life after 1989. It not only filled in a gap before the protracted Eurofighter development, it could also act as an aggressor of sorts for NATO forces.

Some NVA officers grumbled that the Bundeswehr often did not evaluate its equipment properly and generally disdaining most of it. But while this may have an element of truth to it, keeping large quantities of Soviet military equipment was really a non-starter in the post-89 world. Reunification had stoked fears of a resurgent and innately militaristic Germany, and part of the greasing of the 2+4 agreement was that Kohl promised to slash the German military down to a smaller level. Keeping Soviet equipment also meant keeping Soviet suppliers for spare parts, or building German indigenous manufacturing, both of which were economically and politically costly. One of the leverages Kohl had over the Soviets was the massive debts the USSR owed to the FRG, and he was not going to give them a potential out by substituting military spares and replacements for equipment the Bundeswehr did not want. Most of the Category II and III equipment was either scrapped or sent abroad as part of the process of normalizing of the reunified Germany's foreign policy. Some equipment went to the Third World, but a good deal went to the Gulf. The lack of direct German support in the Gulf War caused some tensions within the Western alliance, and Kohl instead opted to use surplus NVA equipment as part of Germany's contribution to the UN forces in Kuwait and Iraq.

Overall, the tale of amalgamation of the NVA and Bundeswehr shows the extreme end of how in the West often called the shots during the reunification process. Bundeswehr chiefs often evinced a disdain for their counterparts and their equipment, and the few NVA troops who found a home in the post-1989 Bundeswehr were few and far between. Like the MfS, the NVA was one of the losers of reunification with many of its career soldiers denied a career in their profession and up to 2005, not even considered German soldiers in official parlance (they were Gedient in fremden Streitkräften (a veteran of foreign armed forces) in state designation). The NVA was likewise blocked out from most of the Ostalgie process (the film NVA being one of the few exceptions) which Easterners wistfully called back the old regime. The close association of the NVA with the SED's state power and coercion makes it much harder to gild in public memory than Spreewald pickles.