There have been attempts to produce a military strength index: this is an example taken from a Credit Suisse report in September 2015. The factors under consideration for that military strength indicator and their total weights were: number of active personnel in the army (5%), tanks (10%), attack helicopters (15%), aircraft (20%), aircraft carriers (25%), and submarines (25%). It was practically impossible to make an estimation of the actual training of the armed forces.  These were the results:
There are two types of military history, although almost all texts have elements of both: descriptive history, that serves to chronicle conflicts without offering any statements about the causes, nature of conduct, the ending, and effects of a conflict; and analytical history, that seeks to offer statements about the causes, nature, ending, and aftermath of conflicts – as a means of deriving knowledge and understanding of conflicts as a whole, and prevent repetition of mistakes in future, to suggest better concepts or methods in employing forces, or to advocate the need for new technology.
In the 2000s, women can serve on U.S. combat ships, including in command roles. They are permitted to serve on submarines. Women can fly military aircraft and make up 2% of all pilots in the U.S. Military. In 2003, Major Kim Campbell was awarded the Distinguished Flying Cross for landing her combat damaged A-10 Thunderbolt II with no hydraulic control and only one functional engine after being struck by hostile fire over Baghdad.