The U.S. Missile Defense Agency, or MDA, continues to sink billions of taxpayer dollars into technology that is not proven to be capable of handling an onslaught of ballistic missile strikes from Iran or North Korea, according to the report, which was issued Tuesday by the Government Accountability Office.

While U.S. military leaders maintain that the current system is likely to defend against “small numbers of simple ballistic missile threats launched from North Korea and Iran,” actual testing of the equipment does not back this claim, according to the report.

As the MDA struggles to develop a working missile defense system, Iran and North Korea are continuing to develop advanced ballistic missile technology with few repercussions from the international community.

The United States will need to redesign and retest key components of its Ground-Based Midcourse Defense, or GMD, system to fulfill presidential mandates ordering that the defense system field 44 interceptors by the end of 2017, a goal oversight officials say it is unlikely to meet.