For all the focus on terrorism, one of the most striking features of the last decade is that the risk of war between the world’s major countries has returned. For the first time since the fall of the Berlin wall, military thinkers in the United States, Europe and Asia are putting serious thought into what such a conflict might look like.

A Chinese paramilitary policeman takes part in a training exercise in Nanning, Guangxi Zhuang Autonomous Region, July 18, 2016. REUTERS/Stringer

For a world with no shortage of nuclear weapons, that’s alarming. As I wrote last month, there is now not just a credible – if still limited – risk of conflict between Russia and NATO states, but also a real risk any such war would go nuclear.

Last week, U.S.-based think tank RAND Corporation – which also studied the prospects of war in the NATO member Baltic states – unveiled its latest thinking on what a potential clash between the United States and China would look like. The report is not direct U.S. government policy – although RAND has long been regarded as a major generator of thought for the U.S. military – but it does push the envelope further than much that has gone before.

The report stresses that while premeditated war between Washington and Beijing ”is very unlikely,” the mishandling of disputes like the multiple territorial confrontations between China and U.S. allies such as Japan and the Philippines are a “danger” that “cannot be ignored.”

RAND examined two different scenarios, one for an inadvertent conflict taking place in the present day and one in 10 years from now, assuming Beijing’s military and economic buildup continues at roughly its current rate. China will substantially close its military gap with the United States over the next decade, it predicts – but the fundamental dynamics of how things will play out might not be hugely different.

Even now, the People’s Liberation Army is seen as having the ability to give a bloodied nose to U.S. forces in the region. Washington could expect to lose an aircraft carrier and multiple other surface warships in the opening stages, RAND warns, citing Chinese advances in ballistic and guided missiles as well as submarines.

The report does not estimate the number of human casualties, but they could be substantial. The loss of an aircraft carrier or several major surface warships could easily cost thousands of lives in an instant.

At the same time, it’s also generally assumed that both Beijing and Washington would have considerable success with cyber attacks.

As another recent report points out, China’s effectiveness would difficult to gauge – not least because it has not participated in a major conflict since invading Vietnam in 1979.

The real decision for Washington would be how much military force to commit to the Asia Pacific theater. Other threats and responsibilities would not have gone away – the Middle East would almost certainly still be a mess and the risk of Russian action in Europe might actually be heightened. Still, the United States would have considerable reserves of aircraft and ships in reserve.

Whether a conflict only endured days or weeks or dragged on for a year or more, Washington would almost certainly retain the ability to strike widely at Chinese targets across the battle space – including, in at least a limited way, into mainland China. Over time, Beijing could face the destruction of most, if not all, of its major surface naval forces. Its relatively primitive submarines would also likely be fairly easy picking, RAND predicts, although that will probably be less true by 2025.

The real battle of attrition, however, would be economic – as it almost always is when great powers confront each other. On that front, the consequences for China could be devastating.

Washington and Beijing are each other’s most significant trading partners. The report estimates that 90 percent of that bilateral trade would cease if the two were in direct military confrontation for a year. That would hurt both sides, but the United States could likely continue trade with much of the rest of the world while almost all imports and exports to China would have to pass by sea through a war zone.

Perhaps most importantly, China might find itself cut off from vital external energy sources while Washington’s energy supply chain would be far less affected.

While RAND estimates a year-long Asian war would take 5-10 percent off U.S. gross domestic product, it believes China’s economy could shrink by up to 25 percent.

These are good reasons why war should never happen. Even if miscalculations pushed both countries to the brink, it’s all but impossible to make a logical argument for either side to push things over the edge. The danger, therefore, would seem to be primarily ill-conceived actions that might cause a World War One-style escalation.

In the case of the United States and China, RAND’s analysts say they believe nuclear escalation would likely be avoided even if both sides fought prolonged naval and air battles. That’s a major departure in Western military thinking from the days of the Cold War, when nuclear escalation was seen an almost inevitable consequence of any direct conventional clash.

Whether that’s certain is a different question. Wars tend to develop their own horrific internal logic and momentum, and the temptation to move to more powerful weapons is ever present.

For now, there’s no evidence that Beijing has adopted Moscow’s thinking on “de-escalatory nuclear strikes,” using a single nuclear warhead in an attempt to shock a Western adversary into standing down and ending the conflict. But it’s possible to imagine that happening.

It’s becoming increasingly important to consider scenarios like these. It we don’t, the unthinkable might quietly – or worse still-- suddenly and brutally become reality.