Ordinarily, to apply for naturalization, you must meet the five-year continuous residence requirement (three years if married to, and living with, the same U.S. citizen spouse for the same period). However, if you work for any of the following entities, you may be able to file an Application to Preserve Residence for Naturalization Purposes (USCIS Form N-470) to preserve your continuous residence in the United States, despite being stationed overseas:
Applying for Citizenship
Citizenship after Marriage to U.S. Citizen