Chemical weapons are pretty strategically bad for how the US engages in warfare. Chemical weapons are great for driving up civilian body count. The US doesn’t really do that as a strategic goal. On the battlefield they have a really high chance of killing and/or permanently disabling your own soldiers. It’s really more of a guerilla’s/terrorist’s class of weapon because it’s good for area denial and wreaking havoc on soft targets.

We absolutely still know how to make them and in fact still have small stockpiles of them.

What we have kept are far below international agreements and are used to test PPE for soldiers who may find themselves being attacked with these bio/chem threats.

We had (literal) tons of chemical weapons during WW2 and never resorted to them.

Truth be told, chemical weapons are generally actually pretty shit. They’re hard to control (which creates potential for both civilian AND friendly casualties), they don’t kill or otherwise put enemies hors de combat particularly reliably, and if both sides end up using them, all that ends up with is a lot of infantry in NBC gear being miserable and not actually increasing the ability of offensives or defensives in any meaningful way.

Anyway, there’s no need to store the info on how to make them because it’s quite literally public knowledge for the most useful and widely used/stored chemical weapons.

We got rid of the “finished and assembled” chemical weapons. The precursors are all ready to be mixed.

Why would we need a long time to store info on how to make them?

US did not use chemical weapons since WW I. Why would we start using them in future wars?