Guest Post: Navy CAPT (Ret.) Pete Pedrozo’s views on “The Right of Transit Passage Through International Straits”

(U.S. Navy photo by Mass Communication Specialist 2nd Class Indra Beaufort).

Yesterday the US Navy announced that the “nuclear-power Ohio-class guided-missile submarine USS Georgia (SSGN 729) along with the guided-missile cruisers USS Port Royal (CG 73) and USS Philippine Sea (CG 58) transited the Strait of Hormuz entering the Arabian Gulf.”  What made this media release so unusual is that the Navy almost never reveals the location of its submarines.  This time, however, it seems the U.S. government intended to send a clear message to Iran.

This U.S. flotilla is an extremely powerful one.  The two Ticonderoga-class cruisers carry an array of sophisticated weaponry and capabilities, and the Ohio-class USS Georgia is the largest submarine in the U.S.’s inventory.  As the Navy announcement points out:

“SSGNs [guided missile submarines] are one of the most versatile platforms in the fleet, equipped with superior communications capabilities and the ability to carry up to 154 Tomahawk land-attack cruise missiles. The platform can also be configured to host up to 66 Special Operations Forces.”

The Tomahawk land-attack missiles (BGM-109) is a highly-lethal (1,000 lb warhead) precision weapon that has a range of 900 nm and is designed to hold at risk heavily defended targets.  It is a proven weapon that the U.S. has used very effectively in the past.  For example, despite bogus Syrian claims about having shot down numerous Tomahawks in the 2017 and 2018 U.S. attacks in response to Syria’s chemical weapon use, the Tomahawk’s targets were devastated.

Though the Navy’s announcement made no mention of Iran, there is little question that the U.S. is sending a warning to the Iranians as January 3rd approaches.  That’s the anniversary of the U.S. drone strike that killed Iranian General Qasem Soleimani, who led the Islamic Revolutionary Guard Corps-Quds Force (a U.S.-designated terrorist organization).  (See here for more about that strike)

Importantly, the Navy also said the”[USS] Georgia’s presence in the U.S. 5th Fleet area of operations (AOO) demonstrates the U.S. Navy’s ability to sail and operate wherever international law allows.”

What then does international law allow in this situation?  After all, the Strait of Hormuz is, as you will read below, “completely overlapped by the territorial sea of Iran, Oman and the United Arab Emirates.”

With Col Tom McCann and CAPT (ret.) Pete Pedrozo, MILOPS Conference, Bangkok, 2019.

Fortunately, we have a real expert to help us sort this out.  Retired Navy Captain Pete Pedrozo, a friend of more than two decades, is also one of the world’s premier authorities on maritime law.  He’s kindly agreed to give us a quick outline as to how the law of the sea applies in situations like this.

Unless you are a maritime law expert, you may be surprised to learn some of the nuances involved when warships transit straits overlapping with territorial seas.  For example, though the Georgia transited while surfaced, she could have lawfully gone through the strait submerged since that is the “normal mode” for a submarine.

However, as once source puts it:

“The depth of Strait of Hormuz (depth of 82 feet to 131 feet) is deep enough for ships, but is shallow for the submarines. The shallow waters and strong currents of the Strait both hamper and aid submarines; the water provides noisy background conditions that help cover up the sound of a submarine, but the shallow waters make the submarine more likely to be visually identified from the air or surface of the water. The confined waters and strong currents of the Gulf make the Strait of Hormuz an extremely hazardous place for even experienced submariners.”

Of course, in this instance the strategic use of the submarine did not require tactical secrecy.  Quite the opposite, the mission called for a very public demonstration that a visible surface passage obviously enhanced.  As the Navy explained:

“As an inherently flexible maneuver force, capable of supporting routine and contingency operations, Georgia’s presence demonstrates the United States’ commitment to regional partners and maritime security with a full spectrum of capabilities to remain ready to defend against any threat at any time.”

Only time will tell if the Iranians got the message and – hopefully – they will temper their behavior accordingly.  In the meantime, let’s have Pete (speaking in his personal capacity) bring us up to speed as to the relevant law of the sea.

The Right of Transit Passage Through International Straits


Raul (Pete) Pedrozo

In a not-so-subtle message to Iran, the USS Georgia (SSGN 729), an Ohio-class nuclear-powered guided-missile submarine, transited the Strait of Hormuz and entered the Arabian Gulf on December 21, 2020. The day before, the United States had accused Iranian backed militias for launching a rocket attack on the U.S. Embassy in Baghdad. The submarine was accompanied by two U.S. surface warships and underscores the right of transit passage in the international law of the sea through straits used for international navigation.

United Nations Convention on the Law of the Sea

The United Nations Convention on the Law of the Sea (UNCLOS) reflects customary international law and recognizes in Part III the right of transit passage through straits. The Strait of Hormuz is an international waterway that connects one part of the high seas or exclusive economic zone (EEZ) to another part of the high seas or EEZ. While the strait is completely overlapped by the territorial sea of Iran, Oman and the United Arab Emirates, the right of transit passage applies in the strait, shoreline-to-shoreline.

While submarines must travel on the surface and show their flag during innocent passage in a typical territorial sea, they may operate underwater “in the normal mode” while transiting in straits that overlap territorial seas.   

Neither Iran nor the US are parties to UNCLOS

Iran is not a party to UNCLOS. However, when Iran signed the treaty in 1982, it did so with a reservation the “only parties to the Convention shall be entitled to benefit from the contractual rights created therein,” thereby purportedly limiting the right of transit passage in Strait of Hormuz to signatories of the Convention.

The United States did not sign UNCLOS in 1982 and is not a party to the Convention. Therefore, Iran considers that the United States does not enjoy unimpeded transit passage rights through the Strait of Hormuz. The U.S. does not recognize this claim and routinely conducts operational assertions with ships and aircraft through the strait.

Since neither Iran nor the United States are party to UNCLOS, their rights and legal relationship at sea derives from customary international law.

Under customary international law, as reflected in Article 38 of UNCLOS, all ships and aircraft, including warships, naval auxiliaries, military aircraft (including unmanned aerial vehicles), and other government-owned or operated non-commercial vessels (including unmanned underwater and surface vehicles) and aircraft, enjoy the right of unimpeded transit passage through such straits and their approaches. The bordering States may not hamper or suspend transit passage (Article 44).

Transit passage

Transit passage means the exercise of the freedom of navigation and overflight, in the normal mode of operation utilized by ships and aircraft, solely for the purpose of continuous and expeditious transit of the strait. That means submarines and unmanned underwater vehicles may transit the strait submerged since that is their normal mode of operation.

As reflected in Article 39 of UNCLOS, while exercising the right of transit passage, ships and aircraft shall (a) proceed without delay through or over the strait; (b) refrain from any threat or use of force against the sovereignty, territorial integrity or political independence of the bordering States; and (c) refrain from any activities other than those incident to their normal modes of continuous and expeditious transit unless rendered necessary by force majeure, distress, or in order to render assistance to persons, ships, or aircraft in danger or distress.

Maritime safety regulations

All ships shall also comply with the International Regulations for Preventing Collisions at Sea (COLREGS), civilian aircraft shall observe the International Civil Aviation Organization Rules of the Air (ICAO ROA), and military aircraft shall operate with due regard for the safety of air navigation. Additionally, ships may not carry out marine scientific research or hydrographic survey activities when engaged in transit passage without the prior consent of the bordering States (UNCLOS Article 40).

UNCLOS Article 42 allows bordering States to adopt laws and regulations related to safety of navigation and regulation of maritime traffic, to include International Maritime Organization (IMO)-approved sea lanes and traffic separation schemes (TSS). Such laws and regulations shall not, however, have the practical effect of denying, hampering, or impairing the right of transit passage.

Routing measures

Merchant vessels shall comply with properly designated IMO-approved sea lanes and TSS. Warships and other government-owned or operated non-commercial vessels (i.e., sovereign immune vessels) may voluntarily comply with IMO-approved routing if practicable and compatible with their military mission but are not legally required to comply. Nonetheless, sovereign immune vessels will always operate with due regard for the safety of navigation and comply with the COLREGS.

About the author:

Captain Raul (Pete) Pedrozo, U.S. Navy (Retired), is the Howard S. Levie Chair on the Law of Armed Conflict and professor of international law at the Stockton Center for International Law, U.S. Naval War College. Prof. Pedrozo was the former senior legal adviser at U.S. Pacific Command and served as special assistant to the Under Secretary of Defense for Policy. The views expressed in this article are his personal views and do not necessarily reflect the views of the United States Government or the Department of Defense

The views expressed by guest authors do not necessarily reflect the views of the Center on Law, Ethics and National Security, or Duke University.

Remember what we like to say on Lawfire®: gather the facts, examine the law, evaluate the arguments – and then decide for yourself!

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