TRUTH, infamously, is the first casualty of war and that’s never more important to remember than after a major tragedy such as the reported strike on a Gaza hospital, with initial death-toll estimates exceeding 500.

It isn’t just the scale and pain of the human loss that has shocked. The event also upended US President Joe Biden’s visit to the region, where he had been due to meet separately with Israeli and Arab leaders on containing the conflict and getting aid to civilians in Gaza.

That latter summit has now been canceled, and inevitably so. Such is the outrage on the Arab Street that no regional leader can afford to be seen negotiating today with Israel’s most important ally. And whereas European lawmakers have avoided attributing blame while condemning the attack, Egypt and Saudi Arabia immediately pointed to Israel.

In a very small pool, Israel is a top suspect: It has been conducting an intense aerial bombing campaign with just the kind of heavy munitions that could collapse a hospital and cause mass casualties. Yet at this point, there are very few things that can be said with certainty, and none concern the details of the attack or its perpetrators.

The first certainty is that Tuesday’s events have brought escalation of the conflict closer, narrowing the space for caution and compromise and increasing support across the region for other state and non-state actors to pile in, should Israel launch its expected ground invasion. No matter what evidence emerges to the contrary, popular opinion across much of the world, especially the Muslim world, will remain convinced that Israel killed more than 500 people in a deliberate and heinous attack on a hospital, which amounts to a war crime.

A second certainty is that there will be more such tragedies for Palestinian non-combatants, and therefore public relations disasters for Israel, if and when it begins its ground attack. The international response already shows that Israel’s stock response — the arguments that Hamas bears ultimate responsibility, and that all wars involve collateral damage — has already lost any power it had to persuade. This needs to be weighed by Prime Minister Benjamin Netanyahu and his war cabinet as they decide not if, but how, to punish Hamas and protect Israeli citizens.

Finally, this is the result of Palestinian civilians being cynically used as pawns, as they have been so often in the intractable Israeli-Palestinian conflict. Hamas has tried to prevent civilians leaving the main battlefield in the North, so it can use them as human shields. Israel, for its part, took responsibility for the well-being of Gaza’s residents when it occupied the space in 1967, and is yet again failing that duty of care, no matter how complex the issue. Egypt has refused to let civilians out of Gaza, saying they should “stand their ground” for the wider Palestinian cause. Iran, at a minimum has cheered the conflict, and more likely helped to plan it, in the hope of scoring just such propaganda victories at the expense of Palestinian and Israeli lives.

When it comes to the facts of the disaster, though, nothing is even remotely clear. Everything about the Israeli reaction since the blast suggests that if it was responsible, something went badly wrong. For Israel, a strike on a crowded hospital can only bring strategic loss. The Israel Defense Forces (IDF) have rushed out purported evidence aimed at showing the cause of the hospital fire was a failed missile launched by Palestinian Islamic Jihad, a political rival and wartime partner of Hamas. The group has denied responsibility. Hamas has accused Israel.

The IDF exhibits include a video of a misfired rocket launch from within Gaza that it says was recorded at precisely the time the hospital was hit; before-and-after satellite images of the hospital that show no signs of the cratering a heavy aerial bomb would cause; images of damage to the hospital roof and adjacent parking lot that would be consistent with a missile that broke up as it fell to the ground, with the main cause of destruction not an explosion but a burning payload of accelerant; and an alleged recording of two Hamas operatives speaking by phone about how  the missile was “one of ours.” On Wednesday, Biden said he’d been shown evidence by the Pentagon suggesting Israel wasn’t responsible for the deadly blast at a Gaza City hospital.

None of this has been verified and, given what’s at stake, nothing either side presents or claims can be accepted at face value. In almost every war ever conducted, governments have shown they aren’t above deception. Distrust of officials and their props in the context of war is not a judgment, but a requirement.

By the same token, few of the allegations from Hamas or its health authority have been independently verified either. That includes claims about the strike itself, its origin, and the number of casualties — which, at more than 500, would be extremely rare for a single strike, though certainly conceivable in a densely packed hospital.

We need to withhold judgment as to responsibility for this monstrous attack until the facts have been verified. In the meantime, the loss of innocent Palestinian life is there for all to see. It argues that Biden’s visit and the role of diplomacy in trying to prevent further escalation and civilian bloodshed have increased just as much in importance as in difficulty.

BLOOMBERG OPINION