Whilethe world has been distracted by the COVID 19 pandemic, dangerous US-Iran incidents in the Gulf have proliferated and could lead to another military clash, or even war.

On 22 April US President Donald Trump tweeted that he had instructed the U.S. Navy to shoot down and destroy any and all Iran gunboats if they harass our ships at sea. The head of Irans Islamic Revolutionary Guard Corps (IRGC) responded that We have also ordered our military units at sea that if a vessel or military unit of the navy of the U.S. terrorist military seeks to threaten the security of our civilian ships or combat vessels, they should target that vessel or military unit. Such bellicose rhetoric does not auger well given the near extreme tension between the two. If US naval commanders on site follow Trumps dictum, this could become the first war initiated by tweet. But before the U.S. uses harassment of its formidable warships by relatively small and lightly armed Iranian gunboats as an excuse to waltz into yet another war, there are many questions that beg answers. These include exactly what happened, who, where, when and why, and what are the implications for future incidents.

As context, the US Congress has failed to override President Donald Trumps veto of its resolution to constrain presidential authority to use military force against Iran without its approval. Particularly worrying is that in its veto notice, the White House acknowledged that it interprets Congresss 2002 Iraq Authorization for Use of Military Force to include military action against Iran.

Given this new context, did Trumps tweet change the Navys rules of engagement? According to the New York Times, the normal rules for escalation of force start at audible warnings and progress through flares, maneuvers, warning shots and as a last resort fire for effect. The former chief of the Pentagons Middle East policy said that harassment is not a direct threat and would not normally elicit a fire for effect response. Moreover, a tweet does not appear to constitute a military order and thus there has been no formal policy directive changing the rules of engagement in responding to provocations by Iranian gunboats.

What happened and why? Trumps tweet was prompted by a 15 April incident in which Iranian naval vessels allegedly made dangerous and harassing approaches toward a fleet of six US Navy ships conducting training operations in international waters. Specifically, the Navy said 11 Iranian ships crossed the bows and sterns of the U.S. vessels at extremely close range and high speeds. Video shot by the U.S. Navy seems to confirm the dangerous approaches.

But Iran claims that on April 6 and 7, U.S. warships interfered with the freedom of navigation of an Iranian IRGC warship by obstructing its path with dangerous maneuvers when the ship was returning from a mission near Farsi Island. Iran said that in response, on April 15, it sent the 11 gunboats to practice live fire at sea in that area and that is when the incident occurred. It may be that both are guilty of violating international law that establishes the “rules of the road” to prevent collisions.

The sensitiveness of Farsi Island may also have played a role. It is a tiny rock in the middle of the Gulf claimed and occupied by Iran. It has a lighthouse and an IRGC Navy base. This base figured in previous US-Iran confrontations. In the late 1980s, during the Tanker War, the IRGC used speedboats based on Farsi Island to attack vessels of Iraq and its allies, including Kuwait. It also was used as a base from which to lay naval mines on the route of the first US convoys sent to protect shipping at that time. Then on 12 January 2016 Farsi - based IRGC boats arrested two small US military vessels that in an embarrassing mistake, accidentally entered Iranian territorial waters around Farsi. Although the US vessels and sailors were promptly released, Navy commanders are still probably smarting from the screw up on their watch. Probably related to the growing US concern is that –according to it– Iran recently violated its word and UN sanctions by launching a military satellite.

What is the legal context of these and similar likely future incidents? The U.S. said its vessels were operating in international waters and that the dangerous and provocative actions [of the Iranian small boats] increased the risk of miscalculation and collision _ _ and were not in accordance with the obligation under international law to act with due regard for the safety of other vessels in the area. This appears to be so. But if U.S. warships obstructed the path of an Iranian warship on 6 and 7 April, the same would apply to it. The US has so far been silent on this earlier incident.

The legal context depends in part on where the incidents occurred and what the US vessels were doing. The U.S. said they occurred in the international waters. It unilaterally uses and defines this term as comprising all waters seaward of the territorial sea [in which] the high seas freedoms of navigation and over flight are preserved to the international community. But there is no such thing as international waters in the UN Convention on the Law of the Sea (UNCLOS).

In this case, the US use of the term apparently refers to the Iranian claimed Exclusive Economic Zone (EEZ). There is a legal disagreement between the two as to what foreign warships can do in such a zone. Iran bans Foreign military activities and practices _ _ inconsistent with the rights and interests of the Islamic Republic of Iran in the exclusive economic zone and the continental shelf. The U.S. strongly objects to this provision. But Iran is not alone in this extreme interpretation of UNCLOS. Someeighteen States including in Asia, China, Malaysia, India, Pakistan and US ally Thailand - - try to regulate or prohibit foreign military activities in their EEZs.

Moreover, according to UNCLOS, in a coastal states EEZ, other states must paydue regard to its rights and duties, including its own freedom of navigation.But the two disagree on the meaning of due regard. But since neither has ratified UNCLOS they have little credibility or legitimacy unilaterally interpreting it and invoking it to their advantage.

If the April 6 and 7 incidents occurred in Irans claimed EEZ, the U.S. warships were violating Irans law its interpretation of due regard.

Going forward, we must be careful that some misunderstanding - or a purposely contrived incident does not become a Gulf of Tonkin-like excuse for yet another war. The Gulf of Tonkin incident refers to an alleged confrontation between US Navy vessels and Vietnamese gunboats that was misrepresented by the US government to justify war against Vietnam.

Given their starkly opposing legal and political positions, the increasingly provocative actions by both sides and their ever more belligerent rhetoric enhance the danger of an incident escalating into open conflict. But there are many unanswered questions that need to be addressed before the US wanders into another war.