US President Donald Trump's team has ordered the termination of vital support for F-16 fighter jet jamming equipment that Ukraine has. What is important to understand is that this could deprive the Ukrainian Air Force of its most important air countermeasures.
There is an aftermarket for F-16 planes and their spare parts.
Also, I should note that Iran (of all countries) is still flying its F-14 Tomcats, unless I’m mistaken.
The most immediate effect is ceasing updates for then AN/ALQ-131 countermeasures pod. If Russians come with a new radar or make their existing weapons behave differently, this could have considerable effect on the survivability of an F-16 in a hot situation.
A lot of F16 parts were manufactured in Europe as well, it was part of the deal to buy the aircrafts.
I’ve worked for multiple aerospace companies in Belgium and Switzerland that were manufacturing f16 parts.
The Ukrainians were already doing those updates for their non American jets, I think they’ll probably be okay in that realm.