In the absence of delimitation, there are competing sets of sovereignty or sovereign rights of two States over the same area, which also imply exclusivity. This lies at the heart of why possible conflicts may occur between States. Different variants of overlapping claims can occur between States: that is, as regards internal waters, territorial seas, contiguous zones, EEZs, (extended) continental shelves and archipelagic waters. Varying with the type of disputed maritime zone involved, specific international law questions arise. Both claimant coastal States and third States can be affected by the existence of disputed maritime areas. For claimant States, questions arise around the extent to which rights can, and obligations have to, be exercised. For third States, or their nationals, questions arise concerning how to exercise rights that may have been obtained from one claimant State, and what obligations they must observe when acting, or seeking to act, in a disputed area. As State practice exemplifies, where a claimant, or a national of a third State, has undertaken unilateral conduct in a disputed maritime area, for example concerning mineral resources or fisheries, which regularly prompts the other claimant into responding – including, by taking law enforcement measures.