15 of the most expensive projects abandoned by the US military

But throughout the 2000s, the Pentagon spent $51.2 billion on 15 major programs "without any fielded systems to show for it," according to a new Center for Strategic and International Studies report.

The abandoned projects are largely due to a lack of funding attributed to the Budget Control Act and sequestration.

Sequestration, which is indiscriminate budget cuts across-the-board that affect every portion of the military equally, is the greatest threat to the US military currently, Former Defense Secretary Robert Gates told Business Insider.

Below are a series of military modernization projects that were canceled partially due to a lack of funds.