# Under what circumstances can you intercept another nation's ships on the high seas? **URL:** \ **Category:** Factual Questions\ **Created:** [May 10, 2008, 4:26am UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783 "2008-05-10T04:26:59Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![astro](https://avatars.discourse-cdn.com/v4/letter/a/9dc877/32.png) [@astro](https://boards.straightdope.com/u/astro)\ **Post date:** [May 10, 2008, 4:26am UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/1 "2008-05-10T04:26:59Z")
The high seas seem pretty free [per this agreement.](http://fletcher.tufts.edu/multi/texts/BH364.txt) Can we legally intercept another nation’s military ships on the high seas if we are not at war with them? Could we stop a North Korean Naval ship on the high seas if we thought they were smuggling weapons? ---
**Author:** ![Declan](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@Declan](https://boards.straightdope.com/u/Declan)\ **Post date:** [May 10, 2008, 6:23am UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/2 "2008-05-10T06:23:48Z")
[QUOTE=astro] The high seas seem pretty free [per this agreement.](http://fletcher.tufts.edu/multi/texts/BH364.txt) Can we legally intercept another nation’s military ships on the high seas if we are not at war with them? Could we stop a North Korean Naval ship on the high seas if we thought they were smuggling weapons? [/QUOTE] I dont think any of the norkom merchant marine vessels are civillian operated and while it was’nt a war ship a north korean vessel was stopped and boarded for supplying no dong missile bodys to Iran , I believe. As for the interception , I would think only in the case just prior to going to war , you would be advised to do that. Declan ---
**Author:** ![KlondikeGeoff](https://avatars.discourse-cdn.com/v4/letter/k/3e96dc/32.png) [@KlondikeGeoff](https://boards.straightdope.com/u/KlondikeGeoff)\ **Post date:** [May 10, 2008, 4:09pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/3 "2008-05-10T16:09:28Z")
**Under what circumstances can you intercept another nation’s ships on the high seas?** If you are a pirate. ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [May 10, 2008, 4:19pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/4 "2008-05-10T16:19:39Z")
> [@](#): > > 1. Except where acts of interference derive from powers conferred by treaty, a warship which encounters on the high seas a foreign ship, other than a ship entitled to complete immunity in accordance with articles 95 and 96, is not justified in boarding it unless there is reasonable ground for suspecting that: > > (a) the ship is engaged in piracy; > > (b) the ship is engaged in the slave trade; > > (c) the ship is engaged in unauthorized broadcasting and the flag State of the warship has jurisdiction under article 109; > > (d) the ship is without nationality; or > > (e) though flying a foreign flag or refusing to show its flag, the ship is, in reality, of the same nationality as the warship. > > 1. In the cases provided for in paragraph 1, the warship may proceed to verify the ship’s right to fly its flag. To this end, it may send a boat under the command of an officer to the suspected ship. If suspicion remains after the documents have been checked, it may proceed to a further examination on board the ship, which must be carried out with all possible consideration. > **[PREAMBLE TO THE UNITED NATIONS CONVENTION ON THE LAW OF THE SEA](https://www.un.org/Depts/los/convention_agreements/texts/unclos/part7.htm)** Warships, specifically: Article95 Immunity of warships on the high seas > [@](#): > > Warships on the high seas have complete immunity from the jurisdiction of any State other than the flag State. \*Id. \* There are other provisions that provide for arrest of vessels in some cases. ---
**Author:** ![aldiboronti](https://avatars.discourse-cdn.com/v4/letter/a/9fc348/32.png) [@aldiboronti](https://boards.straightdope.com/u/aldiboronti)\ **Post date:** [May 10, 2008, 4:29pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/5 "2008-05-10T16:29:21Z")
How about if a blockade has been declared? Was the US legally justified in intercepting Russian shipping bound for Cuba at the time of the missile crisis? (Can’t recall if any ships were actually intercepted, I think the Russians turned back of their own accord.) ---
**Author:** ![Gfactor](https://avatars.discourse-cdn.com/v4/letter/g/9de053/32.png) [@Gfactor](https://boards.straightdope.com/u/Gfactor)\ **Post date:** [May 10, 2008, 5:05pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/6 "2008-05-10T17:05:15Z")
[QUOTE=aldiboronti] How about if a blockade has been declared? Was the US legally justified in intercepting Russian shipping bound for Cuba at the time of the missile crisis? (Can’t recall if any ships were actually intercepted, I think the Russians turned back of their own accord.) [/QUOTE] Here is an article noting the illegality of a NATO blockade of oil to Yugoslavia: [http://www.asil.org/insights/insigh34.htm](http://www.asil.org/insights/insigh34.htm) and > [@](#): > > However, a naval blockade is, prima facie, a violation of freedom of the HS. Such efforts constitute a violation of international law if not conducted with the authorization of the United Nations Security Council pursuant to Chapter VII of the Charter. [http://dsp-psd.pwgsc.gc.ca/Collection-R/LoPBdP/BP/bp322-e.htm](http://dsp-psd.pwgsc.gc.ca/Collection-R/LoPBdP/BP/bp322-e.htm) So based just on the law of the sea, it’s problematic. As I understand it, Kennedy called it a quarrantine in order to blur the distinction. [http://www.cnn.com/SPECIALS/cold.war/episodes/10/documents/kennedy.speech/](http://www.cnn.com/SPECIALS/cold.war/episodes/10/documents/kennedy.speech/) And his Under Secretary of State noted: > [@](#): > > (e) The quarantine would be resented by several of our NATO friends, including the UK, which never acknowledged its legality. They acquiesced before because the limited quarantine did not affect their trade; they might well refuse to recognize a blockade which cut off valuable shipping of POL–particularly since there is a fairly widespread feeling that we have already won our point by expelling the missiles. [http://www.yale.edu/lawweb/avalon/diplomacy/forrel/cuba/cuba169.htm](http://www.yale.edu/lawweb/avalon/diplomacy/forrel/cuba/cuba169.htm) ---
**Author:** ![chowder](https://avatars.discourse-cdn.com/v4/letter/c/977dab/32.png) [@chowder](https://boards.straightdope.com/u/chowder)\ **Post date:** [May 10, 2008, 5:22pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/7 "2008-05-10T17:22:05Z")
[QUOTE=KlondikeGeoff] **Under what circumstances can you intercept another nation’s ships on the high seas?** If you are a pirate. [/QUOTE] Aaarrrrrr 😛 ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [May 10, 2008, 5:46pm UTC](https://boards.straightdope.com/t/under-what-circumstances-can-you-intercept-another-nations-ships-on-the-high-seas/448783/8 "2008-05-10T17:46:06Z")
**Gfactor** is correct in citing the [UN Convention on the Law of the Seas](http://en.wikisource.org/wiki/United_Nations_Convention_on_the_Law_of_the_Sea) (which to further complicate the matter, has not been ratified by the U.S.), but the article he’s citing explicitly covers only ships “other than a ship entitled to complete immunity in accordance with articles 95 and 96.” The OP is explicitly asking about military ships, which are accorded immunity under article 95 of said convention, as he pointed out. That excludes them from the scope of application of the quoted provision. Because of this immunity, I think intercepting a foreign military vessel would almost always (i.e., if not justified by the special circumstances of emergency) be an act of war. Maybe it could be justified under the right of hot pursuit (article 111 of the convention), which applies if a ship has been found in a country’s internal or teritorial waters of a state violating the laws of that state. Hot pursuit makes it possible to go after the ship even if it reaches the high seas during the hunt.