Forgot to mention even the original 150 F-16A/Bs sold to Taiwan in the 1990s were downgraded.
The current version during this period was the F-16C/D Block 50.
Taiwan wasn't sold this version but instead sold the F-16A/B Block 20. The Block 20 was effectively a Block 15 OCU with some elements of Block 50. Still it was downgraded – for example it didn't have the current AN/APG-68 of the Block 50 but rather an uprated older AN/APG-66 which still lacked the range and capabilities of the AN/APG-68.
I guess this was fine when China operated J-6 (MiG-19) and J-7s (MiG-21) but China was already acquiring Su-27s at the time and had signed a licence production agreement for them!
A great example of how the US has been turning the screws on Taiwanese defence capabilities since the 1970s!
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The US formally began limiting arms sales to Taiwan in 1982 when they signed a Joint Communique with China that promised to reduce arms sales.
However it started in the 1970s. Note Taiwan was not provided with F-4 Phantoms in the 1970s even though South Korea was. South Korea started sending F-5As to South Vietnam and in turn received F-4Ds (and then was allowed to buy F-4Es).
Taiwan also supplied F-5As to South Vietnam and in turn got F-5E Tiger IIs and was then allowed to buy more F-5Es.
US was unwilling to provide anything more complicated than an F-5E up to 1992 despite Taiwan requesting F-16s from the early 1980s!
So between 1970 and 1992 ROCAF suffered a massive decline in quality. Other than F-5E/F they were only able to procure some replacement F-100s in the 1970s (A models upgraded to include elements of D model) F-104s in the 1970s and 1980s.
The Navy and Army are in similar states – indeed Taiwan is one of the few places where the M48 Patton derivatives still plays a vital role as well as the M41 Walker Bulldog and other 1960s relics.
For the naval afficandos, 2 of the 4 submarines are WWII vintage Tench and Balao class subs commissioned in 1945 ad 1946 respectively! The remaining 2 aren't that new either, dating from the 1980s but based on a 1960s Dutch design.
But no one has been willing to sell them any submarines since the 1980s (indeed Dutch stopped sales once China turned on the screws in early 1990s!).