The United Arab Emirates on Saturday introduced military service, compulsory for men aged between 18 and 30, state news agency WAM announced.
A law on military service was brought in under the UAE constitution, which stipulates "the defence of the federation is a sacred duty for every citizen," WAM said.
Emirati nationals account for only around 20 percent of the population of oil-rich UAE, a seven-member federation.
Abu Dhabi announced plans to introduce military service in January.
Emirati men who have finished secondary school will serve for nine months, while others will have to enrol in the armed forces for two years.
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Service is optional for women and depends on their guardian's consent.
In November, Qatar's government approved a draft law on military service.
Qatari men between 18 and 35 will have to serve for three months if they are university graduates, and four if they are not.
Kuwait is debating the return of compulsory military service, scrapped after Iraq invaded the emirate in 1990 and occupied it for seven months.
Military service is not compulsory in the other three Gulf monarchies, with Saudi Arabia, Bahrain and Oman employing professional armies.
The trend towards compulsory military service in the Sunni monarchies comes at a time of strained ties with non-Arab Shiite Iran across the Gulf.