Under a UNSCR?
It is worth mentioning that United Nations Security Council Resolutions at various times have changed the circumstances in which warships can use
Straits and archipelagos 93 force at sea. Those resolutions that have authorised forcefill action at sea have primarily concerned the interception of civilian vessels, whether merchant ships in the case of Southern Rhodesia, Iraq, Yugoslavia, Haiti, and Libya, pirate vessels in the case of Somalia, or migrant vessels in the case of Libya again. The only circumstances contemplating warships using force against other warships involved aimed conflict in the case of Iraq in 1990-1991 and Korea between 1950 and 1953. This leaves the question as to whether a United Nations Security Council Resolution could authorise the use of force to keep an international strait open, or even an archipelagic sea lane. Given the character of the other resolutions authorising the use of force at sea it seems quite arguable that the Security Council could give such an authorisation to use ‘all necessaiy means’ to ensure vessels can pass through a particular route. There has been no suggestion of this occurring in respect of the Strait of Hormuz but is worth noting that it appears to be possible as far as the law is concerned, even if it is not politically feasible. The next question is what ‘all necessaiy means’ could be in respect of the use of force. This could amount to non-lethal measures to clear mines or even lethal measures to prevent surface or air attacks launching from bases in the vicinity. The considerations would essentially be the same as those discussed previously. The key difference would be that the authority, and legitimacy, of a United Nations Security Council Resolution would do much to limit questions as to the legality of a mission to keep an international strait or archipelagic sea lane open to international navigation. There may still be questions over particular actions within the mission as being excessive, even if the mission itself is authorised.
The need for a United Nations Security Council Resolution in respect of other maritime zones seem less likely. Navigation in international waters does not have the same concerns about sovereignty that would require such a resolution. An obstruction to navigation in the territorial sea is less likelyto be significant in the way that it would be in an international strait or archipelagic sea lane.
International straits have generated and continue to generate considerable international tension as choke points for both trade and the movement of warships. The deliberate blocking of a strait could be a threat to peace and security, and the non-suspendable right of transit passage under the 1982 Convention reflects this. Even so, in light of the Corfu Channel Case, it is hard to argue that foreign warships could conduct a deliberate operation to clear mines, booms, nets, vessels or other obstructions in an international strait. This could only really occur as a part of a continuous and expeditious exercise of transit passage, being an incidental and immediate form of self-defence of the vessels engaged in that passage. On the other hand, it is much easier to argue that warships may condirct escort operations through international straits. The Oil Platforms Case acknowledged the ‘Earnest Will’ escort missions of the United States in the Gulf, and they appear to be an exercise of passage in the normal mode.
Archipelagic sea lanes present different considerations due to their somewhat different legal characteristics and significantly different geographical characteristics. Unlike transit passage, the right of archipelagic sea-lanes passage does not apply to vessels making a port visit in the coastal state. It is harder, therefore, to describe archipelagic sea lanes as ‘highways’ -anything other than continuous and expeditious passage right through the archipelagic state must be in innocent passage. Archipelagic sea lanes also present a much larger body of water that can traverse right through the middle of a nation, such as Indonesia. A deliberate operation to clear mines or other obstructions in an archipelagic sea lane wottld be a much greater-affront to the peace, good order and sectuity of the archipelagic state. Similarly, the archipelagic state would be responsible for the security of shipping through its waters. Except where armed conflict is occurring between the archipelagic state and a state conducting archipelagic sea-lanes passage, having warships escorting civilian ships through an archipelago would only be likely to be lawful where it was to protect against a threat from outside the archipelago.
-  See James Kraska and Raul Pedrozo, International Maritime Security Law (Martinus Nijhoff Publishers, 2013) 903-921; see also Rob McLaughlin, 'United Nations Mandated Naval Interdiction Operations in the Territorial Sea?’ (2002) 51(2) International and Comparative Law Quarterly 249 2 UN SCOR, 1277th mtg UN Doc S/Res/221 (1966) 3 UN SCOR, 2938th mtg UN Doc S/Res/665 (1990) 4 UN SCOR, 3137th mtg UN Doc S/Res/787 (1992) 5 UN SCOR, 4987th mtg UN Doc S/Res/917 (1994) 6 UN SCOR, 6498th mtg UN Doc S/Res/1973 (2011) 7 UN SCOR, 5902nd mtg UN Doc S/Res/1816 (2008) 8 UN SCOR, 7531st mtg, UN Doc S/RES/2240 (2015) 9 UN SCOR, 2963rd mtg, UN Doc S/RES/678 (1990) 10 UN SCOR, 476th mtg, UN Doc S/RES/84 (1950)