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.
Ballistic and Cruise Missile Threat (PDF)
Also maybe you think we should not defend all our military personnel stationed in Europe, or maybe you think we should pull out all our troops and run home with our tails between our legs, either way, such foolish behavior is not in America's strategic interests.