With very few exceptions, becoming a non-commissioned officer (NCO) or petty officer in the U.S. Armed Forces is accomplished by progression through the lower enlisted ranks. However, unlike promotion through the lower enlisted tier, promotion to NCO is generally competitive. NCO ranks begin at E-4 or E-5, depending upon service and are generally attained between three and six years of service. Junior NCOs function as first-line supervisors and squad leaders, training the junior enlisted in their duties and guiding their career advancement.
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.
Military history is often considered to be the history of all conflicts, not just the history of the state militaries. It differs somewhat from the history of war, with military history focusing on the people and institutions of war-making, while the history of war focuses on the evolution of war itself in the face of changing technology, governments, and geography.
The last requirement of the military is for military performance assessment, and learning from it. These two functions are performed by military historians and military theorists who seek to identify failures and success of the armed force, and integrate corrections into the military reform, with the aim of producing an improved force capable of performing adequately, should there be a national defence policy review.
By military department, $146.9 billion was allocated for the Department of the Army, $168.8 billion for the Department of the Navy, $161.8 billion for the Department of the Air Force and $102.8 billion for DoD-wide spending. By function, $138.6 billion was requested for personnel, $244.4 billion for operations and maintenance, $118.9 billion for procurement, $69.0 billion for research and development, $1.3 billion for revolving and management funds, $6.9 billion for military construction and $1.3 billion for family housing.
Personnel may be recruited or conscripted, depending on the system chosen by the state. Most military personnel are males; the minority proportion of female personnel varyies internationally (approximately 3% in India, 10% in the UK, 13% in Sweden, 16% in the US, and 27% in South Africa). While two-thirds of states now recruit or conscript only adults, as of 2017 50 states still relied partly on children under the age of 18 (usually aged 16 or 17) to staff their armed forces.
International protocols restrict the use, or have even created international bans on weapons, notably weapons of mass destruction (WMD). International conventions define what constitutes a war crime, and provides for war crimes prosecution. Individual countries also have elaborate codes of military justice, an example being the United States' Uniform Code of Military Justice that can lead to court martial for military personnel found guilty of war crimes.
Under the Student Loan Repayment Program, when you enlist the Army will pay back up to $65,000 in qualified education loans (up to $20,000 for reservists), the Navy up to $65,000 and the Air Force up to $10,000. Each year 15% of the loan balance or $500, whichever is greater, will be repaid by SLRP. There may also be annual and cumulative caps on the amount repaid. Participants must score 50 or higher on the Armed Forces Qualifications Test (AFQT). SLRP must be requested at the time of enlistment or reenlistment. Qualified education loans include federal education loans such as the Perkins, Stafford, PLUS, or Consolidation loans, but not private alternative loans. Defaulted loans are not eligible. Payments made under the SLRP are considered taxable income.
Since then, the advances made by human societies, and that of weapons, has been irretrievably linked. Stone weapons gave way to Bronze Age weapons, and later, the Iron Age weapons. With each technological change, was realised some tangible increase in military capability, such as through greater effectiveness of a sharper edge in defeating leather armour, or improved density of materials used in manufacture of weapons.
Although some groups engaged in combat, such as militants or resistance movements, refer to themselves using military terminology, notably 'Army' or 'Front', none have had the structure of a national military to justify the reference, and usually have had to rely on support of outside national militaries. They also use these terms to conceal from the MI their true capabilities, and to impress potential ideological recruits.
Examinees also receive a score on what is called the Armed Forces Qualification Test (AFQT). AFQT scores are computed using the Standard Scores from four ASVAB subtests: Arithmetic Reasoning (AR), Mathematics Knowledge (MK), Paragraph Comprehension (PC), and Word Knowledge (WK). AFQT scores are reported as percentiles between 1-99. An AFQT percentile score indicates the percentage of examinees in a reference group that scored at or below that particular score. For current AFQT scores, the reference group is a sample of 18 to 23 year old youth who took the ASVAB as part of a national norming study conducted in 1997. Thus, an AFQT score of 90 indicates that the examinee scored as well as or better than 90% of the nationally-representative sample of 18 to 23 year old youth. An AFQT score of 50 indicates that the examinee scored as well as or better than 50% of the nationally-representative sample.