Latin American states are mounting a challenge to the acceptance of a legal standard promoted by the US, UK and their allies to justify military operations in the Middle East, fearing the same standard could eventually be used to justify intervention in their own hemisphere.

The Mexican government is spearheading an effort at the UN to bring greater transparency to the formal legal justifications presented by western powers for military operations in Syria and elsewhere.

Latin American states say that one of the most important questions in international law – when is it permissible to wage war on another country’s territory – is being settled by stealth, by a small group of military powers, with no global debate.

States involved in the counter-Isis campaign and other foreign military operations have submitted letters of justification for their actions to the UN, citing self-defence against the threat of terrorism and arguing in many cases that the governments of the countries involved have been “unwilling or unable” to deal with the threat. The letters have typically been submitted after the military operations have taken place.

Writing for the legal website, JustSecurity, on Tuesday, the legal adviser to the Mexican UN mission, Pablo Arrocha Olabuenaga, said: “The debate regarding the legitimacy and relevance of the ‘unwilling or unable’ standard to use force against terrorist groups has so far been largely dominated by a few western states.”

Olabuenaga argues that the lack of a concerted pushback so far against the use of such self-defence arguments under Article 51 of the UN charter should not be interpreted as consent. Rather, it is a reflection of the lack of transparency of the UN system. The submission of Article 51 letters to the security council justifying a military operation is not publicised. They eventually appear on a security council archive, known as the repertoire, but that is currently two years out of date.

“Most member states are left in the dark,” Olabuenaga writes.

The JustSecurity article is written in his personal capacity, but he stresses that the concerns are shared widely across Latin America. Last October, 33 countries represented by the Community of Latin American and Caribbean States, issued a statement raising concern about the increase in Article 51 letters being sent to the security council justifying the use of force in counter-terrorism operations.

“Of course it’s relevant whether states communicate their claims of justifications publicly or whether they obscure them,” said Paulina Starski, senior research fellow at the Max Planck Institute in Heidelberg. “This is one more reason to doubt whether ‘unwilling or unable’ has consolidated as a legal standard and represents an accurate interpretation of Article 51.”

Unease in Latin America has been heightened by Donald Trump’s recent rhetoric. He accused the Mexican armed forces of being “unable or unwilling” to stop columns of migrants reaching the US border, and in March he said he was thinking “very seriously” about designating Mexican drug cartels as terrorist organisations.

The US secretary of state, Mike Pompeo, claimed in February there were Hezbollah “active cells” in Venezuela, and declared: “We have an obligation to take down that risk for America.”

The US secretary of state. Mike Pompeo. Photograph: Cliff Owen/AP

The evolution of the “unwilling or unable” standard reaches back to George W Bush’s “global war on terror”. After failing to agree with the European Union on a legal standard to justify foreign military operations, John Bellinger, a state department legal adviser, convened a meeting in 2007 of national security lawyers from the UK, Australia, Canada and few other close allies at the West Point military academy.

Over the next decade, the little-known “West Point group” hammered out a set of principles, including the “unwilling or unable” standard, to underpin the use of Article 51 self-defence justifications for the use of force, in particular against non-state groups in the Middle East.

When Jeh Johnson, the general counsel at the Pentagon in the Obama administration, compiled a memo to justify the raid on Osama bin Laden’s compound in Abbottabad in 2011, he is reported to have drawn on the work of the West Point group in arguing controversially that Pakistan was “unwilling or unable” to deal with Bin Laden itself.

The former legal adviser to the UK foreign office, Sir Daniel Bethlehem, set out a similar set of principles in a 2012 article for the American Journal of International Law. President François Hollande cited Article 51 as justification for French military intervention in Mali in 2013. Over the past five years, most of the 13 countries have invoked the right of self-defence under the UN charter to launch attacks on groups deemed to be terrorist threats, most of them in Syria, without the consent of the Damascus government.

“There is a sense that the security council and international law in general have so profoundly failed in the Syria case that even critics of US policy could understand why US behaved the way it did,” said Richard Gowan, the UN director at the International Crisis Group.

“But there is mounting concern in general that as the security council and the UN system grinds to a halt, it gives the US and others the leeway to just consistently flag Article 51 and bomb away.”

A Latin American diplomat acknowledged the severity of the challenges to international law in Syria, but argued that if the security council was deadlocked it should pass the issue to the UN general assembly to resolve, rather than confecting open-ended legal grounds for military intervention.

“The threat of Isis is very grave, but our concern is that even though you are doing this today for that reason, if you open the door to these exceptions, the precedent you set goes beyond Isis, and raises questions of whether you can intervene on other grounds,” said the diplomat, who did not want to be named because of the sensitivity of the issues involved.

“Transnational organised crime is a non-state actor in our region. If other governments can say this threatens their international peace and security, that is very dangerous.”