These interceptors are for missiles from Iran.
The first question I would have is that if these are to defend Europe from Iran then why does Cruz think that building it will send a message to Russia? The second question is, what missiles? There are no missiles from Iran capable of reaching the U.S. And the chances that there ever will be are non-existent. There longest ranged missile comes up short of the U.S. by about 6000 miles.