The enormity of what is at stake in the international crisis following last week's atrocities in New York and Washington was brought home yesterday as the world absorbed President Bush's non-negotiable ultimatum to the Taliban government in Afghanistan.
It amounts to a declaration of war against that regime and implies that military action against it is being seriously planned in the short as well as the longer term. Political leaders in Europe and throughout the world are having to factor in this probability as they consider the fallout from the crisis. The same applies to world stock markets, which have fallen steeply as the spectre of recession looms.
Rarely has such a huge change happened in such a short space of time. In Ireland as elsewhere in Europe the consequences are profound for politics, economics and security. Last night's special European Council in Brussels underlined the EU's solidarity with the United States, affirmed its determination to co-operate against terrorism and sought to reassure those who are fearful about the economic impact of the crisis that the European economy's fundamentals remain sound. The sheer fluidity of these events is clearly indicated in the rapidity with which they have convinced the Provisional IRA to re-engage with the de Chastelain commission and by speculative reports last night that the organisation has decided to put some of its arms dumps beyond use.
That would indeed be a silver lining to a dark cloud that has threatened Ireland for so long.
President Bush's speech to Congress on Thursday night successfully rallied its members and the citizens of the United States, a remarkable 79 per cent of whom are reported to have watched the broadcast and most of whom warmly approve its tone and substance. He was well served by his speech writers, just as he has been well served by his security team in their diplomatic and military response to the disaster.
Mr Bush emphasised that this was an attack not only on Americans but on humanity at large. He called for those responsible to be brought to justice not revenge. He warned that there will be a long campaign against the perpetrators of such acts, in which intelligence can be as important as military hardware. And he reached out to Muslims in the US and around the world to join in a campaign against terrorism, seeking to head off any civilisational conflict. These are all positive signals, affirming American internationalism and partnership with its friends and allies and relieving reservations about the president's leadership capacity.
Mr Bush went on to insist on his country's right of self-defence against such attacks and to prepare its people for possible imminent military engagement. A week of extraordinarily intense diplomatic and military activity has begun to assemble a broad international coalition, based on US leadership and loosely mandated by an inclusive United Nations Security Council resolution passed last week concerning these atrocities and the worldwide threats they represent.
The real test of that coalition's effectiveness will come in coming days and weeks. Military experts warn about the dangers of becoming involved in a long term engagement in Afghanistan, arising from a rapid attack on ill-defined targets. Reports that a more audacious approach is under way, effectively to topple the Taliban regime in alliance with Afghan rebels and replace it with a United Nations interim administration which would deliver up the chief suspect, Osama bin Laden and his organisation, are unconfirmed, but would need the most careful planning and UN endorsement.
From Ireland and Europe there has come profound solidarity with the US administration and people, which was reaffirmed at last night's EU summit. There is concern that the crisis be handled with proper regard for military proportionality and well targeted. There should be due legal process through the UN and in bringing those responsible to justice. There should also be a full awareness that any campaign against terrorism is long drawn out, requiring patience, good intelligence and a readiness to respond politically to grievances that sustain it. Such concerns were affirmed in this week's special sitting of the Oireachtas and at last night's Brussels meeting. There are encouraging signs that they are being heard in Washington - and they must not be drowned out in any rush to war.
The European Council pledged to create a common anti-terrorist programme in coming months, including common lists of organisations, closer police co-operation and a common definition of what the term terrorism means. That is a difficult and politically a very sensitive task, since the word is freely used to demonise as enemies those who oppose existing political, social or economic structures. Too permissive a definition could help create and not contain the violent instability in which terrorist groups thrive, dangerously threatening existing civil liberties. Vigilance will be needed to ensure such groups do not achieve their aim of undermining the democratic structures they oppose by forcing governments to over-react - for example by using these new powers against globalisation protesters who should instead be engaged in political dialogue.
Vigilance will also be needed to ensure that the worldwide coalition being assembled against terrorism is inclusive and attentive to the appeal of such extremism in pools of human misery and poverty. Ill-directed military action could easily add to their number, rebounding against those who plan it.