McCain called on the Navy to justify the purchasing of the ship, which still hasn’t been fully tested to see if it operates as needed to complete the Navy missions.

“To justify the purchase of the remaining 32 ships in the program, the Navy must first provide credible evidence, based on rigorous, operationally relevant and realistic testing and evaluation, that this ship will in fact be able to adequately perform its primary stated missions and meet combatant commander requirements,” McCain said. “Congress must, at a minimum, thoroughly review this program before authorizing funding in fiscal year 2015 to buy the next four LCSs.”

The Senate could consider the National Defense Appropriation Act (NDAA) — the defense spending bill — when it returns from the month-long August recess. McCain, who serves on the Armed Services Committee, has been critical of the more than $40 billion Navy program because he said the “Navy plans to buy the ships before knowing if the ships will work as advertised.”

McCain added that taxpayer money has already been wasted on numerous other failed military contracts, but said Congress should be especially careful now considering the massive budget cuts facing the Pentagon as a result of sequestration.