The Trump administration is seeking a significant expansion in the Ground-based Midcourse Defense program – a missile defense system on which the United States has already spent some 67 billion. Since the Ground-based Midcourse Defense system was declared, more than 15 years ago, to have achieved initial operational capability, tests of the system have failed more often than they have succeeded, despite their having been conducted under artificially simplified conditions. The system does not dissuade nations such as North Korea from developing intercontinental missiles; it likely would not deter North Korea or Iran from attacking the United States; and it would almost certainly fail to provide effective defense against a real attack. Meanwhile, because Russia and China have legitimate reasons to perceive the Ground-based Midcourse Defense system as a potential threat, they have incentives to improve or expand their nuclear capabilities. Despite all this, the program has faced little meaningful resistance in Congress or in successive presidential administrations – a reality that is unlikely to change soon.