Remember when Russian forces were massing on the Ukrainian border and a lot of people staked their argument against war on insisting that Russia would not invade? Over the past few days I’ve seen the exact same mistake again. Twice.

First time came on Thursday in reaction to Russia’s horrific attack on a hospital in the southern city of Mariupol — sparking, of course, yet another round of calls for NATO to get involved. Taking on the calls for intervention, right-wing media activist Michael Tracey insisted that the attack’s 17 injuries did not have “any independent corroboration,” adding that such

details are pretty important considering Zelensky is citing this incident as evidence of “genocide,” which would be the ultimate justification for a “humanitarian intervention”[.]

This, it turns out, was an absolutely terrible argument, since the World Health Organization had in fact independently corroborated 17 injuries.1 Terrible for Tracey, since it looks an awful lot like he was spreading false information in order to cast doubt on the magnitude of an actual war crime; but terrible for antiwar activists too, since those confirmed injuries supposedly provide “the ultimate justification for a humanitarian intervention.”

The very next day, a similar scenario played out when Russian ambassador Vasily Nebenzia warned the United Nations of “US military-purpose biological activity in Ukraine that creates real risks for international peace and security.”

This, US ambassador Linda Thomas-Greenfield replied, was Russia’s attempt to “fabricate allegations about chemical or biological weapons to justify its own violent attacks against the Ukrainian people”; and ever since, the antiwar left has labored to establish that the alleged bioweapon labs are indeed fake news.

I’m not going to pit my guesses and intuitions about this against the absolutely absurd number of US-Ukraine joint bioresearch program wonks with security clearances who are hashing this out in the discourse right now, but I will ask the antiwar left a question: even if Russia’s allegations were vindicated, what would this change about the case against war?

A million pundits have already compared Russia’s claim about WMDs in Ukraine to the US’s lie about WMDs in Iraq, with the obvious upshot that this case for war is probably fraudulent too. Most of these comparisons, however, seem to be forgetting that the case against war in Iraq was much bigger than “there aren’t WMDs.” The left also argued that states cannot be permitted to launch “pre-emptive strikes” against each other and that they should not proceed unilaterally as opposed to working within the UN. These were our most potent arguments against war for a long time, in fact, because it was only well after the fact that Americans generally concluded that WMDs had not been and would not be found.

Which brings us to the broader point: the best arguments against war are arguments that do not depend on controversial questions of fact. This was true weeks ago when so many on the left staked their case against war on the prediction that Russia would not invade Ukraine; this was true when interventionists insisted that NATO would have to respond by insisting that 17 people were injured in the attacks on the Mariupol hospital; and it is true today as the Kremlin suggests that it had the right to launch a unilateral pre-emptive strike against Ukraine.

This is one of the greatest advantages that the antiwar left has against the hawks and we should never lightly abandon it. There just aren’t many possible questions of fact that can ever justify going to war. When someone claims they’ve found one, your first instinct shouldn’t be to dispute whether or not the claim is true; it should be to insist that even if it is true, it wouldn’t justify anything. This frames the controversy correctly, it keeps the standard of justification high, and it puts the hawks in the difficult situation of having to establish their claim and having to insist that it matters.

The United States should not be funding the development of bioweapons anywhere in the world, including Ukraine, and also including the United States. Given NATO’s aggressive military expansion to Russia’s borders and the US’s past lies about its operations in Ukraine, the Kremlin has every reason to be suspicious. If Ukraine attacked Russia with WMDs, Russia would of course have a right to self-defense. One can even argue that it would have the right to defend itself from an imminent attack that had not yet materialized, though this is where questions of justification become ambiguous.

And yet with all of these considerations in mind, there is still zero ambiguity here. The mere development and possession of WMDs cannot justify a unilateral preemptive invasion. Russia’s rightful suspicion of the US and Ukrainian governments cannot justify a unilateral preemptive invasion. Ukraine did not attack Russia with WMDs, and Russia did not even allege that such an attack was imminent before invading.

It’s significant, by the way, that Thomas-Greenfield did not make these points in her comments before the Security Council and focused on the question of fact instead. The US has never been above hypocrisy in international affairs, but there are obvious reasons why Washington will avoid arguing that unilateral warfare and pre-emptive strikes are illegitimate if it can. Something any anti-imperialist with an ounce of sense should probably bear in mind.