In the immediate aftermath of the Mumbai attacks, wild speculations swirled, furious cyclones that threw up windy and wild theories, charged conspiracies and noisy condemnation. Inevitable perhaps, just human nature responding fearfully to sudden and unspeakable violence. The terrorists cleaved the body, heart and soul of this cosmopolitan, enterprising hub which draws to its bosom the richest and most wretched of the earth. What they did coldly in hotels, cafés and the Jewish centre was as atrocious as the killings in Beslan. But as the panic subsides, it is the duty of all world citizens to confront truths, however inconvenient.

Instead we see a scandalous passing of the buck. "Can't be, won't be, not our native sons," say India, Pakistan and Britain as they set about impugning each other explicitly and implicitly. It is a form of post-trauma nationalism that can grip wounded nations and was most vividly manifested in the US after 9/11. Meanwhile, millions of Muslims, also traumatised, habitually revisit sites of conflict – Palestine, Kashmir, Afghanistan and Iraq – or list other legitimate grievances to explain away each successive act of Islamist violence.

Denial and obfuscation once again stop us from examining who the killers were, why they did what they did, the places and times they pick. It is not to exonerate them or forgive them, but to acquire vital data and a deeper understanding of the international networks and the mental states of the perpetrators – their religious and political ideologies. This essential information cannot be extracted through torture or the outlandish "evidence" of anti-Muslim, neo-con think tanks whose agenda we know all too well.

Download the new Independent Premium app Sharing the full story, not just the headlines

Years on from the al-Qa'ida assault on the US, with two wars still going on, Guantanamo Bay and other rendition centres doing their filthy work, Islamist assassins can still strike in Mumbai. We have no psychological profiling, no dependable evidence to stop the next time. Is that not chilling? As big a problem is the pathological reluctance of nations to examine how their politics and policies bear some responsibility for the support given to men of terror.

Take India. Its people, economy, history, culture and democratic credentials make it a remarkable country. It is also a nation which tolerates shocking poverty, inequality, caste and religious injustice and gender oppression. Some Indian Muslims have done brilliantly well in the last decade or so, too many though are trapped in poverty and have fallen below the lowest of the Hindu castes.

Prime Minister Manmohan Singh appears sanguine about this Muslim underclass and has done little to bring to trial those responsible for the massacres of Muslims in Gujarat. Nothing is done to quell the physical abuse and oppression of Kashmiris by the Indian security services. Even if the terrorists came from Pakistan – there must be Muslims in India who feel unsafe in their land and so support the unsupportable. Ashok Mehta, a security analyst, says: "Without help, the terrorists would not have known how to enter the hotels or where the exits are. This operation would have been well-rehearsed and there certainly would have been local guides." That kind of talk is taboo in complacent India.

Then there are the deniers, who are outraged if you suggest that Pakistan breeds Islamists who terrorise their own country. Ahmed Rashid is one of the world's most authoritative Pakistani authors. His latest book, Decent Into Chaos: The US And The Failure Of Nation-Building In Pakistan, Afghanistan And Central Asia, tells how his country is now increasingly lawless, churning out young people filled with homicidal aspirations. Many in the political and military establishment back the jihadis. I said so on the BBC this weekend and was then forced to shelter from the torrent of abuse from "patriotic" Pakistanis. Sara writes: "Just because these men were Muslims doesn't mean they were the financiers." The men were probably Indian double agents, says another Pakistani. A man from Burnley calls me "a fucking Zionist". Don't ask me why.

Here, after some early, irresponsible coverage claimed some of the killers were British, there is now an assumption that there is no connection at all. I think we need to wait and see. The Government still refuses to accept the implicit contribution that our foreign policies have made, and as yet has commissioned no credible, long-term research on radicalisation.

After Obama's victory, the world felt optimistic. That India and Pakistan (a democracy again) were at last trying to rebuild trust gave pause for cautious hope. The Mumbai terrorists shattered all that and once more, we are lost in misinformation and misapprehension.

y.alibhai-brown@independent.co.uk