Can't launch P-3 for ASW attack

After Unknown Sub Group OOU is detected, I attempt to launch a P-3 from Base AAa to attack. I went through all the normal steps to select the number and type of aircraft, but after executing the order, I get a window that says "Sir, we have no released weapons available to conduct an ASW attack". If I launch the aircraft on some other pretext and then order it to attack directly, all goes normally.