Pedra Branca, Singapore ceded by the Government of the State of Johore or in any other way disposed of". The Acting State Secretary of Johor replied on 21 September that "the Johore Government does not claim ownership of Pedra Branca". This correspondence indicated that as of 1953 Johor understood it did not have sovereignty over Pedra Branca, which had therefore vested in the United Kingdom. The Colony of Singapore became a self-governing state in 1959, and left the British Empire to join the Federation of Malaysia in 1963. Two years later, in 1965, Singapore became a fully independent republic. In 1959, in an
Federation independence from the sovereign state, which only takes care of their foreign relations and defence. However, they are neither considered to be part of it, nor recognised as sovereign or associated states. The distinction between a federation and a unitary state is often quite ambiguous. A unitary state may closely resemble a federation in structure and, while a central government may possess the theoretical right to revoke the autonomy of a self-governing region, it may be politically difficult for it to do so in practice. The self-governing regions of some unitary states also often enjoy greater autonomy than those of