The United States is involved in operations against nations and organizations that counter its economic and political interests in an area. Given that the United States and its allies—such as Turkey, Iran, Israel, etc.—have weapons capable of CBRN attacks, the existence of these weapons are not the issue for the US. Rather, the United States seeks to maintain control of areas to ensure its power, wealth, and access to resources across the globe.
For example, the US was a strategic ally to the Kurdish people for almost a decade in order to counter ISIS because the US understands ISIS to be a threat to US control and security. However, once Turkey invaded Rojava (an autonomous region in Syria), the United States made a strategic exit from the northern border of Syria, leaving two weeks before the invasion. This opened the door for the Turkish invasion, which has led to the mass deaths and suffering of the people of Northern Syria.
There is a growing case against the Turkish army, as Turkey is accused of using white phosphorus attacks against the people of Rojava in the invasion, in October 2019. Yet the United States essentially gave the go-ahead for the Turkish invasion of Rojava. Clearly, any efforts by the US to counter CBRN attacks are made from positions of political and economic interest rather than ethics or humanitarian concern.