What do Britons "want" in the coming year? An ambassador to Washington was once asked the question on radio and replied, "That's very kind of you, a box of candied fruits would do." Such humble responses are now out of date. As the season of goodwill slithers into that of New Year's resolution, the urge to tell the world how to behave seems uncontrollable.

We can suppress a yawn at David Cameron's sermon on Christian values and Ed Miliband claiming the Helmand army is making Britain "secure, peaceful and happy". More troubling is the foreign secretary, William Hague's, declaration on Facebook of a Christmas ambition to increase "international pressure on Syria … push Burma in the right direction … improve the situation in Somalia … and protect women's rights in the Middle East" among other uplifting goals.

The phraseology may seem in place beneath portraits of Pitt and Palmerston, but how must it play with its intended recipients? Imagine the Indian foreign minister sending Britons a Christmas message deploring their addiction to knife crime, or Japan's expressing his dismay at Britain's broken homes, or Pakistan's decrying Ulster sectarianism as "unacceptable". I am sure Hague would tell them to mind their own business.

Britain's assumption of an ancestral role in passing judgment on Kipling's "lesser tribes without the law" seems genetically embedded. Hague might as well have been quoting from The White Man's Burden, how he must "fill full the mouth of famine / And bid the sickness cease", even if it meant watching "sloth and heathen Folly / Bring all your hopes to nought". His tour of the horizon boasted of "saving lives" in Libya, but he was more detached over Syria. He glided past Iraq, Iran and Afghanistan, preferring the clearer ethical waters of Sudan, Somalia, Burma and Muslim women's rights.

None of the areas of Hague's concern had anything to do with Britain, let alone being within Britain's sovereign domain, nor have they been for over half a century. The power has gone. The legitimacy has departed. Only the language of implied command echoes through the Foreign Office's post-imperial dusk.

That echo is far from an irrelevance. It has conditioned surely the most catastrophic decade in British foreign policy since the 1930s. Another soldier died in Helmand over Christmas, where soldiers will go on dying, to no clear purpose, until 2014. Another hundred Iraqis died in Baghdad bombings, the outcome of Britain's shared incompetence in restructuring Iraq. Meanwhile, around 5,000 have died in Syria, screaming against the double standard that toppled regimes in oil-rich Iraq and Libya but leaves Syria to empty sanctions and emptier rhetoric.

Over this last decade Britain's national sovereignty has not been remotely threatened by any other state, yet its government has adopted a stance of hectoring and often open belligerence towards much of the Muslim world. British forces have been sent to ill-judged and ineptly fought wars that have left British cities in a state of perpetual terrorist alert. It is hard to think of any gain to Britain's foreign interests that has come from these wars – apart from a possible anticipated oil deal in Libya.

The reason goes back in part to Lady Thatcher's commitment to "hug close" to Washington in the later years of the cold war. The hug came to be a suicide embrace, since most of the subsequent mistakes have derived from America's over-reaction to 9/11, leading to mendacious excuses and wars of regime change and destabilisation. Whatever the evils of the Ba'athist and Taliban regimes, they cannot have justified such colossal loss of life, dislocation and destruction. Today we hear the same warlike language towards Iran. Do we really think the security of the region or the lot of the Iranian people can possibly be improved by future British or US military action? The Libyan intervention removed a dictator at relatively small cost, but how is that Nato's business, any more than it is to dispose of dictators in Africa and Asia?

With the end of the nuclear threat, a revived resort to war as a foreign policy response seems to run deep in British and American psyches. Television programmes and bestseller lists are fixated on the two world wars. Britons consume tales of past horror and cruelty. We excuse a harping on the trenches, on Hitler, on D-Day and on the blitz as a warning to each generation that these were "the wars to end all wars". Like the bombing of Hiroshima and Nagasaki, they are portrayed as exemplary deterrents against the use of such dreadful weapons ever again.

I begin to wonder. The west's readiness to resort to violence in the aftermath of the cold war suggests something more sinister. The publicity now accorded to political oppression anywhere in the world is a standing casus belli for the military elites of Nato, the UN, the US and Britain. Not a day passes without some global horror being presented to the west's interventionists with a demand that "something must be done".

Pity is a noble urge, but its effect is not always wise. Contemplating the outcome of the second world war, Hannah Arendt warned pity could "possess a greater capacity for cruelty than cruelty itself". It becomes the ubiquitous pretext, the excuse. How often is the cruelty of Saddam or the Taliban used to justify western atrocities in Iraq and Afghanistan? How many more Syrians must die, a BBC reporter asks, "before we do something?" The something is, of course, the ever desirable war.

Most citizens regard war as a car crash, a random, irrational event that just happens. They do not see it as the outcome of a political process to which as democrats they are party. War may still be occasioned by pity, clothed in the language of humanitarianism, but it has become a casual, media-guided and exploited pity. A lot of people have a lot of money at stake in pity, and it goes far beyond the UN's emergency relief fund.

Hence the suspicion that the obsession of so many Britons with past violence and present cruelty is no longer deterring them from risking its repetition, but the opposite. It makes them ready, almost eager, for more. The path from the cosy interventionism of a Christmas-tide foreign secretary to the sabre rattling, drone-killing, suicide bombing and destruction of the last decade is not as wide as might seem. Such intervention is not so much the white man's burden as his morbid thrill.