The fastest American response to a submarine raid on New York

How would the US Navy improve anti-submarine warfare after an Italian submarine attack on New York?

It would probably buy many more British-built escorts, especially Flower-class corvettes, while domestic capacity caught up.

The counterfactual imagines Leonardo da Vinci surviving long enough to support an attack near New York. The emergency procurement response matters more than the raid's spectacle. The quickest way to increase American anti-submarine strength would be to purchase from British escort lines already producing ships. Since the United States historically acquired some Flower-class corvettes, the crisis would expand an existing route rather than invent a new one.