NATO and the U.S. military use the same phonetic alphabet, and it is widely accepted and used in international radio communications on the sea, air, or land.
The International Radiotelephony Spelling Alphabet (IRSA) is its proper name, and it was created by the International Civil Aviation Organization (ICAO) to help decipher similar sounding letters and numbers between different countries and organizations.
When you are spelling out a name, location, code, registration number, postcode etc, over a noisy or faint radio or phone link, it is easy for letters and numbers to be misheard.
Using the phonetic alphabet to spell out names, locations and so on makes accurately understanding messages a lot easier, because many letters can be easily confused when heard over a crackly radio link (B, C, D, P, T and M, N and F, S, etc).
The standard "NATO" phonetic alphabet (actually the International Radio-Telephony Spelling Alphabet) is:
Alfa, Bravo, Charlie, Delta, Echo, Foxtrot, Golf, Hotel, India, Juliett, Kilo, Lima, Mike, November, Oscar, Papa, Quebec, Romeo, Sierra, Tango, Uniform, Victor, Whiskey, X-ray, Yankee, Zulu.
Numbers are pronounced as normal, except often 9 is pronounced "Niner" so it doesn't get confused with 5.
It is called the "NATO" alphabet because it was standardised by the NATO member countries back in the 1950s to allow accurate exchange of radio messages between air, naval and army forces of all the NATO member nations.
They had to make sure that each chosen word sounded different to the others, and was easily pronounceable by speakers of all the European languages, not just in English.
It is now very widely used by all types of "professional communicators" including air traffic control, the police and other emergency services, shipping, etc and in all types of business.
The phonetic alphabet is a list of words used to identify letters in a message transmitted by radio, telephone, and encrypted messages. The phonetic alphabet can also be signaled with flags, lights, and Morse Code.
When on the radio, spoken words from an approved list are substituted for letters. For example, the word "Army" would be "Alfa Romeo Mike Yankee" when spelled in the phonetic alphabet. This practice helps to prevent confusion between similar sounding letters, such as "m" and "n," and to clarify signals communications that may be garbled during transmission.
In military missions, the use of the phonetic alphabet has been used to communicate with the chain of command as to what phase of the mission has been successfully performed. For instance, if a SEAL Team has arrived on the beach and were undetected to continue the mission, they may have designated that as the first "waypoint" and use the code word "Alpha." It will tell the upper-level chain of command where they are and if they are on schedule.
An early version of the phonetic alphabet appears in the 1913 edition of The Navy Bluejackets’ Manual. Found in the Signals section, it was paired with the Alphabetical Code Flags defined in the International Code. Both the meanings of the flags (the letter which they represent) and their names (which make up the phonetic alphabet) were selected by international agreement. Later editions included the Morse code signal as well.
The Navy and other seafaring vessels use the visual symbol on the mast of the ship/boats to convey the status of the ship and crew. From emergencies to dredging operations and other occupations being accomplished by the boat and crew, flags are a way of communicating on the open waterways. As seen in the picture, all flags represent the phonetic alphabet and have meanings different than the above chart.
The use of alpha-phonetic symbols is to decrease radio traffic and to communicate status or request assistance in code that can be understood internationally. The more tactical use of alpha-phonetics can be used similarly as code words to mission status, encrypted, and decrease open radio traffic with a line of sight communications with flags and lights.
Here are some common military uses of the phonetic alphabet used in both official military communications as well as the informal: