It is not yet clear exactly when, or even whether, the next round of “peace talks” on Syria might take place. Nevertheless, one thing is already clear: More and more parties involved in the Syrian conflict are showing signs of readiness to tackle the fundamental causes of what remains the new century’s greatest human tragedy.

Without a doubt, one of those causes is the speedy “falling out of love” of the Syrian people with a regime that had dominated their nation since 1970.

This does not mean that Syrians loved the Assad regime even at its best or least bad.

What it means is that many Syrians, perhaps even a majority, were prepared to tolerate it the way one tolerates bad weather. Those who visited Syria during the reign of the two Assads always noticed a sentiment that the French call “desamour”, a term that means a sense of “un-loving” that, in time, leads to intense hatred.

Thus, a consensus is taking shape, even in such unexpected places as Moscow and Tehran, that the departure of President Bashar al-Assad from power must, at some point, be considered as inevitable.

A year ago, Moscow and Tehran regarded Assad’s departure as “non-negotiable”. At the same time, the Western democracies, with the exception of Obama’s bizarre administration, insisted it was a sine qua non for a peaceful settlement.

Since then, both sides have modified their positions.

Moscow and Tehran no longer reject any talk of an eventual retirement for Assad.

In contrast London and now Washington under the new Trump administration send signals that they no longer demand that Assad step down as a precondition for a peaceful settlement.

Easing Assad out of the equation faces a number of difficulties. The first of these is the length of any transition that leads to his departure. Assad wants to remain until the end of his presidential mandate, that is to say another five years at least.

Western powers, however, insist on a transition of 12 to 18 months.

As a sweetener, British Foreign Secretary Boris Johnson has suggested that, at the end of a brief transition, Assad may be allowed to stand for re-election. Johnson’s offer may sound like fools’ gold because it is unlikely that Assad would have any chance in any election not organized by himself.

Nevertheless, the gesture could bridge the gap between Western powers and the pro-Assad camp led by Russia.

The length of transition, however, isn’t the only problem. Assad and his protectors also need to settle the thorny problem where and for how long the deposed ruler and his immediate entourage might spend the rest of their life. If our information is correct, neither Tehran nor Moscow wish to play host to a group that would be a magnet for revenge operations by those who have so terribly suffered in recent years. And, yet, finding a host country that could also guarantee the safety of Assad and his entourage is no easy task.

An even more complicated issue concerns the guarantee that Assad wants against prosecution for war crimes and crimes against humanity.

The problem is that the way the corpus of international law related to war crime sand crimes against humanity has developed in the past three decades makes the prospect of such a guarantee hard to imagine.

For almost a century the concept of sovereign immunity shielded government, leaders against charges of war crimes and crimes against humanity. Though substantially eroded at the trial of Nazi party leaders in Nuremberg, the concept maintained half a life of its own until the 1990s. There was consensus that one could bring a state to justice, albeit in civil suits seeking financial compensation and/or restitution of illegally confiscated property while making it impossible to prosecute individual officials of a state.

In the past quarter of a century a new consensus has taken shape, leading to the Rome Protocols and the creation of the International Criminal Court endorsed by the overwhelming majority of the United Nations members. Today, except in very rare cases, the principle of Sovereign Immunity does not cover individual officials of a state even at the highest levels.

Another significant development is the disappearance of “status of limitation” as a legal concept. Until two or three decades, acts that might be classified as war crimes were subject to time limits beyond which no successfully prosecution was possible. Now, however, war crimes and crimes against humanity remain open to prosecution for ever. Thus, regardless of how long he might live, Assad would always remain a target for prosecution on charges of war crimes and crimes against humanity. That principle was most dramatically established in the case of Charles Taylor, a former Liberian President involved in war crimes in Sierra Leone, and the cases of Serbian leaders Slobodan Milosevic, Radovan Karadzic and Ratko Mladic.

Despite informal guarantees offered by France and a number of its African allies, number of African former leaders, among them Chad’s Hicene Habre, fall in the same category.

Yet another major change concerns the development of a new approach to rules of evidence.

In some instances, for example the trial of Khmer Rouge leaders in Cambodia, evidence presented in war crimes cases consisted almost entirely of testimonies by individual victims and/or their survivors and was, thus, vulnerable to cross-examination.

Now, however, many governments systematically collect evidence regarding war crimes and crimes against humanity. The U.S. State Department, for example, has a special Office of Global criminal Justice that advises the Secretary of State and the Under Secretary of State for Civilian Security, Democracy, and Human Rights on issues related to war crimes, crimes against humanity, and genocide.

Between 2012 and 2013 the office had a special project regarding the conflict in Syria and amassed a mass of evidence on Assad’s alleged war crimes and crimes against humanity. As a gesture of goodwill towards the Islamic Republic in Tehran, in 2013 President Obama shut down the project and transferred its budget. Nevertheless, the evidence collected is intact and could be used in any eventual cases against Assad and his entourage.

Other nations, including in Denmark and Germany have also collected evidence regarding Syria, at times in conjunction with the Independent International Commission of Inquiry on Syria (IICIS).

German Chancellor Angela Merkel has publicly accused Assad’s troops of committing “crimes against humanity” that could not be overlooked.

“The use of barrel bombs and incendiary bombs, and even chemical weapons, is not being shied away from,” Merkel said in November 2016 in Berlin.

“The civilian population is being starved, medical institutes are being attacked, doctors are dying and hospitals are being destroyed,” she said, adding that not even United Nations aid convoys were safe from bombardment.

For its part the IICIS has published a number of reports, most recently regarding the systematic massacre of detainees in Syrian prisons run by Assad.

The report states that thousands of detainees held by the regime have been beaten to death or dying from torture.

“Nearly every surviving detainee has emerged from custody having suffered unimaginable abuses,” Paulo Pinheiro, Chair of the IICIS, said of those held by the regime with the title: “Out of sight, out of mind: Deaths in detention in the Syrian Arab Republic.”

Last but not least, scores of Non-governmental organizations (NGOs) and thousands of human rights activists, many of them Syrians, have bene collecting evidence for years.

No other ruler in history has faced such an avalanche of evidence indicating his role in a tragedy. The question is not whether that avalanche will roll down on its object; the only question is: when?