| Country | Government type |
| Southern Ocean | void |
| Spain | parliamentary monarchy |
| Spratly Islands | void |
| Sri Lanka | republic |
| Sudan | Government of National Unity (GNU) - the National Congress Party (NCP) and Sudan People's Liberation Movement (SPLM) formed a power-sharing government under the 2005 Comprehensive Peace Agreement (CPA); the NCP, which came to power by military coup in 1989, is the majority partner; the agreement stipulates national elections in 2009 |
| Suriname | constitutional democracy |
| Svalbard | NA |
| Swaziland | monarchy |
| Sweden | constitutional monarchy |
| Switzerland | formally a confederation but similar in structure to a federal republic |
| Syria | republic under an authoritarian military-dominated regime |
| Taiwan | multiparty democracy |
| Tajikistan | republic |
| Tanzania | republic |
| Thailand | constitutional monarchy |
| Timor-Leste | republic |
| Togo | republic under transition to multiparty democratic rule |
| Tokelau | NA |
| Tonga | constitutional monarchy |
| Trinidad and Tobago | parliamentary democracy |
| Tunisia | republic |
| Turkey | republican parliamentary democracy |
| Turkmenistan | republic; authoritarian presidential rule, with little power outside the executive branch |
| Turks and Caicos Islands | NA |
| Tuvalu | constitutional monarchy with a parliamentary democracy |
| Uganda | republic |
| Ukraine | republic |
| United Arab Emirates | federation with specified powers delegated to the UAE federal government and other powers reserved to member emirates |
| United Kingdom | constitutional monarchy |
| United States | Constitution-based federal republic; strong democratic tradition |
| United States Pacific Island Wildlife Refuges | void |
| Uruguay | constitutional republic |
| Uzbekistan | republic; authoritarian presidential rule, with little power outside the executive branch |
| Vanuatu | parliamentary republic |
| Venezuela | federal republic |
| Vietnam | Communist state |
| Virgin Islands | NA |
| Wake Island | void |
| Wallis and Futuna | NA |
| West Bank | void |
| Western Sahara | legal status of territory and issue of sovereignty unresolved; territory contested by Morocco and Polisario Front (Popular Front for the Liberation of the Saguia el Hamra and Rio de Oro), which in February 1976 formally proclaimed a government-in-exile of the Sahrawi Arab Democratic Republic (SADR), led by President Mohamed ABDELAZIZ; territory partitioned between Morocco and Mauritania in April 1976, with Morocco acquiring northern two-thirds; Mauritania, under pressure from Polisario guerrillas, abandoned all claims to its portion in August 1979; Morocco moved to occupy that sector shortly thereafter and has since asserted administrative control; the Polisario's government-in-exile was seated as an Organization of African Unity (OAU) member in 1984; guerrilla activities continued sporadically until a UN-monitored cease-fire was implemented on 6 September 1991 (Security Council Resolution 690) by the United Nations Mission for the Referendum in Western Sahara or MINURSO |
| World | void |
| Yemen | republic |
| Zambia | republic |
| Zimbabwe | parliamentary democracy |