> did it actually control and had the capacity to use them
A major worry at the time was that individuals in Ukraine could sell those weapons and the know how to the highest bidders.
It wasn't an unlikely prospect - China, Pakistan, and India all bought defense IP from individuals in Ukraine during the collapse of the USSR and before post-Soviet states governance were formalized (eg. China and India can now manufacture Aircraft carriers, nuclear submarines, and turbofan jet engines because of IP they bought using questionable methods in Ukraine in the 1990s)