While UNCLOS is only one of many regimes, or sets of rules, laws, codes and conventions that have been created to regulate the activities of private, commercial and military users of our seas and oceans, it provides the legal framework for further maritime security cooperation.
The United States has not yet ratified UNCLOS (see United States non-ratification of the UNCLOS) but it does adhere to its conventions, and has been the driving force behind other maritime security initiatives, including PSI, CSI, ISPS Code and counter-piracy agreements to address piracy against commercial shipping in the Gulf of Aden, Horn of Africa region.
Complications arise when a navy, coast guard, coastwatch, maritime police force, or other agency wishes to intercept (or 'interdict') vessels suspected of carrying out illegal activities, such as piracy against ships, smuggling or there is potential for an act of terrorism.
If several states within a maritime region (such as the Caribbean Sea or Southeast Asia) can come to agreement on 'hot pursuit' and boarding of suspect vessels, then this will reduce time that must otherwise be spent seeking permission.
Maritime Security in its commercial and military forms has been the primary reason for Naval presence in areas with high shipping traffic but low levels of policing.