Traditionally the freedom of the high seas included the use of the high seas for military maneuvers or exercises, including the use of weapons¹²⁶. This freedom has been incorporated in the 1982 UNCLOS, and it has been generally believed, particularly by maritime States, that this applies also to the EEZ. However, upon signing or ratifying the Convention, several States, including Bangladesh, Brazil, Cape Verde, Pakistan, Malaysia and Uruguay, declared that such kind of military activities are not permitted in the EEZ without the consent of the coastal State¹²⁷. Sharply opposing declarations have been filed by Germany, Italy, the Netherlands and the United Kingdom¹²⁸. The US has also taken the position that "military activities, such as... launching and landing of aircraft, ...exercises, operations ... [in the EEZ] are recognized historic high seas uses that are preserved by Article 58.¹²⁹"

　

 Several commentators stress that Article 58 permits military maneuvers generally within EEZs Without the consent of the coastal State¹³⁰. Others, however, are of the view that the Convention has not given any clear rule on this issue. Thus, Vukas says that the problem of the legality of military maneuvers and ballistic exercises temporarily preventing other States from using a vast area of the high seas remains unresolved¹³¹. While a simple naval maneuver can be considered to be associated with the freedom of navigation, Scovazzi argues that it would be more difficult to sustain, that an extended test of weapons, such as launching torpedoes and firing artillery or the covert laying of arms within an EEZ, are to be included among the uses associated with the operation of ships, aircraft and submarine cables¹³². Churchill and Lowe point out that it is not clear whether such activities as naval exercises involving weapons testing are included within the freedom of navigation and overflight and other internationally lawful uses of the sea related to them¹³³. Lowe has also contended that there are plausible arguments for the reference of a dispute over the legality of naval maneuvers and exercise to Article 59 on residual rights¹³⁴.

　

 It must be concluded from the foregoing that State practice and commentators are divided on whether military maneuvers, and particularly those involving the use of weapons, in the EEZ of a foreign State without its consent are internationally lawful uses of the sea. Commentators tend to argue that naval exercises of reasonable scale without the use of weapons are permitted.

　

 This Guideline language affirms that the conduct of military exercises in the EEZs of other States is allowed. But in the interest of safety and confidence-building it exhorts any State planning major military exercises in the EEZ of another State to inform that State and others of the details in advance, and if possible, to invite observers form the coastal State. To do otherwise, is to court an appearance of arrogance, hostile intent or even a threat of force.

　

 This exhortation is not only common sense but is mandated in part by Article 98(1) (Duty to render assistance). To hamper such operations of the coastal State would not only be considered an unfriendly act but would also violate the due regard principle. Of course this exhortation to co-operate may be qualified by unusual circumstances such as serious danger to the ship, the crew or the passengers.

　

 States are obligated by the UN Charter and the 1982 UNCLOS not to threaten or use force against the security (i.e., the territorial integrity or political independence) of other States. But it is not clear when, where and how the deployment of certain systems might "prejudice the defense or security of the Coastal State". Maritime powers deploy various kinds of devices, installations and structures for military purposes in the sea including in the EEZs of other countries¹³⁵. Examples include sonar monitoring or surveillance systems like acoustic array systems laid on the continental shelf, and navigational aids for submarines and warships. Two approaches have been advanced for justifying the use of such objects for military purposes. One is to interpret them as "other internationally lawful uses of the sea" under Article 58(1), and the other is to consider them as "installations and structures" that under Article 60 would not require the consent of the coastal State.

　

 Regarding the first approach, some authors have argued that certain types of devices, installations and structures for military purposes come under Article 58(1) because they are "uses of the sea related to [the freedom of navigation ... and of laying of submarine cables], such as those associated with the operation of ships ... and submarine cables ... , and compatible with the other provisions of this Convention." For example, according to Rauch, acoustic array systems on the continental shelf, which are networks of large fixed acoustic detection devices linked to shore-based processing units, may be subsumed under the freedom to lay submarine cables since their key functions of transmitting electronic impulses and information to terminals or other receivers have common elements¹³⁶. Churchill and Lowe¹³⁷, Treves¹³⁸ and Boczek¹³⁹ also consider certain types of sensor arrays could be related to the freedom to lay submarine cables. With regard to seabed devices for navigation aids for submarines and other warships, Treves and Boczek argue that they could be considered as being "associated with the operation of ships¹⁴⁰".

　

 For obvious reasons, the use of devices, installations and structures for military purposes is little publicized apart from the well-known fact that the United States and the former USSR deployed the Sonar Surveillance System (SOSUS) and the Soviet Ocean Surveillance System (SOSS) on the continental shelf off the U.S., and in the North Sea and the Mediterranean¹⁴¹. Hence the paucity of relevant practice of States, and a hasty conclusion is not warranted. However, it may tentatively be suggested that the use of devices, installations and structures for military purposes, except weapon systems, would be permitted in the EEZ of another State, subject to the "due regard" requirement.

　

 On the other hand, it should be noted that the deployment of armedmines¹⁴² and other weapon systems would not be justified under Articles 88 and 301, except for the purpose of legitimate self-defense, nor under Article 58 since they are likely to interfere seriously with the exercise of freedom of navigation and other rights in the EEZ¹⁴³ such as the right of the coastal State to protect and manage its resources and environment. The latter would be a failure of the duty of due regard.

　

 One type of military use of the seas that has been relatively overlooked is the deployment and use of expendable marine instruments. These instruments are deployed for collecting data about the water column for use in naval operations including anti-submarine warfare, MSR, and the commercial ocean industry, and are essential to promote safe navigation. Warships and research vessels routinely deploy such instruments extensively while navigating almost any waters. One author estimates that since their introduction 30 years earlier, millions had been deployed worldwide prior to mid-1990s¹⁴⁴. Despite their extensive use, probably because such instruments are not particularly threatening to the coastal environment, apparently coastal States have historically ignored their deployment¹⁴⁵. The legal regime applicable to expendable marine instruments in EEZs Would depend upon whether they are deployed and used for MSR purposes, for navigational purposes, or military purposes including those that might threaten force against the coastal State. In the case of the former, they would generally be subject to the consent regime in Part XIII of the LOS Convention.