A European plug cannot be used directly in the US. European plugs are designed for the electrical systems in Europe, which have different standards from those in the US.

European plugs typically have two round pins, and the diameter and other dimensions of these pins are based on European standards. In contrast, US sockets require plugs with two flat parallel pins (for non - grounded) or two flat parallel pins plus a round grounding pin. The shape and size differences make it physically impossible for a European plug to fit into a US socket.

Moreover, the voltage standards also vary. The standard voltage in Europe is usually in the range of 220 - 240V, while in the US it is 120V. Even if a European plug could be made to fit into a US socket, the voltage difference could potentially damage the electrical device connected to the plug. To use a European - sourced device in the US, you would need a suitable adapter to change the plug shape and, if the device is not designed for a wide voltage range, a voltage converter to adjust the voltage.