Just How Is a Country Recognized?
From the Sealand wiki article:
In international law , the two most common schools of thought for the creation of statehood are the constitutive and declaratory theories of state creation. The constitutive theory was the standard nineteenth-century model of statehood, and the declaratory theory was developed in the twentieth century to address shortcomings of the constitutive theory. In the constitutive theory, a state exists exclusively via recognition by other states. The theory splits on whether this recognition requires "diplomatic recognition" or merely "recognition of existence".