I can't think of anywhere that would have been less appropriate as a venue for this week's Nato summit than the UK.
A United Kingdom that within the next couple of weeks may become shatteringly disunited. A once middle-ranking European power that now has no idea what sort of international role it wants for itself, or indeed whether it even wants to be part of a European Union. A nation that sometimes seems to have decided to have no further truck with any joint international endeavours.
Inward-looking, backward-looking, suspicious of its neighbours: everything that Nato is meant not to be. And this at a time when the world is a more dangerous place than it's been in decades. So why are Western leaders - because it's not just David Cameron - so dismally unable to confront the dangers?
The answer is both simple and complex. Simple, because the world's traditional globo-cop - the US - no longer has either the will or the cash to carry on as before. Its ill-fated military ventures in Afghanistan and Iraq have sapped the Americans' appetite for more wars, and its economic plight means it can no longer afford to fight other people's wars for them.
Good thing too, you may say, when you look at the consequences of the US's most recent forays. But here comes the complex bit: in the absence of a globo-cop, bad people get more chances to do bad things. (Globo-cops can do bad things too, of course: Guantanamo, Abu Ghraib, you can draw up your own list ...) Who should stop the bad people -- and how -- is now the single biggest foreign policy headache facing world leaders.
Nato? Ah yes, good old Nato. The US by another name. As Gideon Rachman pointed out in the Financial Times this week, the US now provides no less than 75% of Nato's total spending, compared to 50% at the height of the Cold War. It may still be the world's biggest economy (just), but it's heartily fed up with European leaders whining about a lack of "American leadership" and then scurrying for cover as soon as someone suggests they might like to cough up some cash themselves.
I remember a senior Nato official telling me some years ago that for effective international action to be agreed, you always need one political leader to go out in front, pick up the phone and do some serious arm-twisting. Tony Blair was pretty good at it (Kosovo, 1999); so were George H.W. Bush (Kuwait, 1991) and Nicolas Sarkozy (Libya, 2011). This time, when it comes to Ukraine, Syria, or Iraq? Er, no one.
As it happens, there are some very good reasons for the reluctance to go back to war. First, recent experience is not encouraging. Second, it's extremely difficult to see what kind of action, at least in Syria or Ukraine, would be effective. Third, there's the very real possibility that military intervention would make things worse rather than better.
There is, however, one Nato member that might be in a position to take up where the US has left off, and that member is Germany. It is the most powerful economy in Europe, and Chancellor Angela Merkel is by a long way Europe's most powerful leader. Germany is also, according to a global opinion poll conducted last year, the most admired country in the world.
There's just one problem: history. The Germans themselves, and the rest of Europe, remember what happened in the past when Germany had ambitions to be a global power, and it did not end well. So whether it's the global economic crisis or Russian troops stomping around in eastern Ukraine, Chancellor Merkel has no intention of dressing up in a globo-cop uniform. I can't say I blame her.
But with the Polish prime minister Donald Tusk now in pole position in Brussels (sorry) as the new president of the European Council, Mrs Merkel really is best placed, together with Mr Tusk, to mediate between Moscow and Kiev. (Britain has no useful role to play, if only because of its unedifying determination not to upset all those Russian oligarchs who like to use the London property market as their playground.)
Let's be clear: even if the latest ceasefire is effective, the Ukraine crisis won't be over until there's a sustainable political settlement. No outside power is going to go to war on Kiev's behalf - that's why at the Nato summit in Bucharest in 2008 (I was there), Western leaders rebuffed Ukraine's attempt to begin a membership application process.
As for Iraq, it seems to me that President ("no strategy yet") Obama is heading slowly in the right direction. Just as the first President Bush did in 1991, he wants to assemble a multi-national coalition that extends beyond the Western powers. That means bringing countries like Turkey on board, plus Jordan and at least some of the Gulf Sunni autocracies. (If they really don't approve of the IS jihadis, now is the time for them to show it. And to do something useful with all that military hardware we keep selling them.)
Most important of all is to engage with Iraq's Sunni leaders to help them confront the brutality of the IS zealots. Because if there is to be any hope for Iraq -- or Syria, or Ukraine -- the shape of the future must be decided by its own people.
Finally, spare a thought for the people of Bama, in northern Nigeria, 26,000 of whom are reported to have fled from their homes after the town was seized by jihadi fighters from Boko Haram, IS's African soul-mates. Bodies are said to be littering the streets.
And if you can, spare another thought for the people of Guinea, Liberia and Sierra Leone, facing the worst outbreak of the Ebola virus in history. According to the president of the international medical relief agency Médecins sans Frontières: "The world is losing the battle to contain it ... cases and deaths continue to surge. Riots are breaking out. Isolation centres are overwhelmed. Health workers on the frontline are becoming infected and are dying in shocking numbers."
If it wasn't for everything else, Nigeria and Ebola would be on the front pages as well.