Max Weber said that the state is a “human community that (successfully) claims the monopoly of the legitimate use of violence within a given territory.” That is a – somewhat brutal – definition of internal sovereignty, the power of the government and constitutional system over people within an autonomous territory. To be a state, however, it is necessary to have external sovereignty as well – that is to say, it must be recognised as a state by other states.
Internal sovereignty is a necessary, but not sufficient, condition for statehood. There must be a territory, and a fixed population, in order to have a government. That government must be the sole governing body, and there must be no higher authority within the state. The UK’s sovereignty is vested in Parliament: this has the power to make and unmake laws, which the judicial system upholds. However, there are currently states which lack internal sovereignty. Libya is a good example: there are three governments, many militias, one external invading force (Da’esh) and great lawlessness. (This political vacuum is setting Libya up for another military dictatorship.)
External sovereignty is the existence of a state according to international politics – the recognition of its existence, and therefore rights to territorial self-rule, by other countries. The UN is the formal channel through which states are recognised, as it represents the (near-) entirety of the international community. However, UN recognition is the recognition by individual states – Kosovo, for example, is recognised by 111 UN members, but not Serbia. Somaliland declared independence a quarter of a century ago, and certainly has internal sovereignty, but is still unrecognised, although it is gaining international status. Abkhazia is unrecognised, but internally sovereign. And Libya’s government is backed by the UN, but has no internal sovereignty.
Iraq’s internal sovereignty was challenged by the USA and UK in 2003, when they invaded it in order to remove Saddam Hussein; this also necessarily challenged its external sovereignty. It is alleged that Russia has been challenging the USA’s internal sovereignty by interfering in elections. Russia cannot be seen to be challenging its external authority, however. It is the recognition of the state’s autonomy that allows North Korea to stumble on uninvaded. Internal sovereignty can also be challenged by TNCs.
Internal and external sovereignty are distinct, but interdependent: either is a necessary condition for statehood; it takes both for a sufficient condition.