The 2023 NDAA, passed in late 2022, included 1700 ATACMS Missiles in a multi-year buy (up to 5 years). That's almost 350/year. Before this order, ATACMS was in low rate production for foreign sales. With all the HIMARS being sold around the world, they might need another production line, or licence some production lines in Europe.
It's really a separate topic, but Europe needs to start building their own short and medium range ballistic missiles.