We live in a world which, not least when it comes to war, is entirely different to that of our fathers and grandfathers. In the old days, from the time the International Committee of the Red Cross (ICRC) was founded in 1863 up until the end of the Korean war, if war was brutal it had a terrible clarity about it. There were opposing armies, enemy lines and conflict which at least purported to maintain a distinction between combatants and civilians, though the bombing raids by both the Germans and the allies in World War Two brought civilians unmistakably into war.

Yet even that "Home Front" was a world away from the state of modern conflict. This is characterised by the guerrilla warfare so typical of today's unequal conflicts, generally between a powerful conventional army and a rag-tag collection of opponents whose armaments are their own suicide bomb-strapped bodies and a ferocious dedication to their cause.

September 11 is only the most acute manifestation of this. All around things have become much messier, with bombs in pizza parlours and on tube trains, hostage-taking, internet executions and private military companies muddying the waters between who is a combatant and who is not. If there can realistically be said to be a "war on terror" then we are all involved.

The job of the Red Cross has had to change in line with all this. In 1977 additions were made to the 1949 Geneva Conventions strengthening the law protecting civilians and the wounded during wartime and insisting that civilians must not be targeted. The ICRC still concerns itself with protecting and assisting victims of conflict. It still provides food and shelter victims, and negotiates with combatants and collects information on violations of international law. But the context of that has shifted significantly.

Today it finds itself in far more delicate negotiations between splintering groups of guerrilla factions. It visits prisoners who are not old-style PoWs but suspected terrorists detained in Guantanamo and elsewhere without due legal process. It deals with the internally displaced as well as those who have been defined as refugees because they have crossed an international boundary. In doing so it has to negotiate legal and diplomatic minefields.

Most of us live with unease as well as uncertainty about this new dispensation. Fear of terrorism has hardened many hearts, publicly and privately. The British Government is ever proposing harsher periods of detention without trial. Half the public, according to a recent Red Cross survey, now believe it is legitimate to target civilians in war, compared with just three in 10 before September 11. Before that 72 per cent of people thought that civilians should be left out of conflict; now only 50 per cent think that.

Yet there is ambiguity in that response. Seventy-six per cent said it was wrong to deny civilians medicine, food and water to weaken the enemy (up from 58 per cent in 1999). And the proportion who thought it illicit to take hostages had grown from 76 per cent to 85 per cent.

But if governments have wilfully clouded the distinction between torture and interrogation as the practice of "waterboarding" and activities in places such as Abu Ghraib have shown there is still a moral clarity among the public with 80 per cent insisting that torture is wrong, even to obtain important military information.

If such ethical judgments are to be transformed into effective practice, the need for an organisation as sure-footed as the ICRC is now greater than ever.

Paul Vallely is Associate editor, The Independent