In g.captain newsletter yesterday they mention cost overrun and delays when building the new Aircraft carriers: http://gcaptain.com/aircraft-carriers-championed-trump-vulnerable-attack/
These modern wonders are vulnerable to attack by simpler and cheaper foreign weapons, yet Trump wants to build more of them.
BTW: The proposed DoD budget increase of $54Bln. could easily have been saved by curtailing wasteful spending according to this WP article: https://www.washingtonpost.com/investigations/pentagon-buries-evidence-of-125-billion-in-bureaucratic-waste/2016/12/05/e0668c76-9af6-11e6-a0ed-ab0774c1eaa5_story.html
But don't worry, Trump will "get a better deal" for your tax $$$
PS> It is not a new problem, or limited to the US, though most of the failed projects in this list of "Biggest Military Wastes of Money" are: http://www.ranker.com/list/biggest-military-wastes-of-money/mike-rothschild