PM wins vote on hitting Isis in Syria, but now comes hard part
The murder of 130 people in Paris by Islamic terrorists proved to be a tipping point in world opinion on the threat posed by Isis and the need to eradicate what has been accurately described as a death cult. In the wake of those ghastly atrocities - and earlier outrages in Lebanon and Egypt - there was a global determination to strike back hard.
The UK, which has agreed to extend its war against the terrorists by beginning to bomb their strongholds in Syria, had little other option. There was a moral obligation to support the pleas from France for help, and opening the new front had the legal authority of the UN, where a resolution to that effect was passed.
If the UK had not taken last night's decision its standing as a world power and a trusted military ally would have been severely diminished.
While the debate on whether to bomb or not stirred up strong emotions on all sides of the House - and almost caused civil war in Labour ranks - essentially it was the easiest task that Prime Minister David Cameron will face on the war against Isis. The UK is already bombing the terrorists in Iraq, and with France, Russia, the US and several Arab nations involved in air raids in Syria, it is not a huge stretch for the RAF to join them.
But it is what happens next that will cause the Prime Minister and the people of the UK the most soul-searching.
Inevitably, no matter what the assurances of precision targeting and smart bombs are, there are civilians alive in Syria today who will not be in the days, weeks and months ahead as the bombing campaign intensifies.
Isis, whose barbarism knows no bounds, will have no problems using men, women and children as human shields.
In any case, every bombing campaign has collateral damage - a euphemism for the killing of the innocent and the uninvolved.
In addition, Mr Cameron has been told repeatedly by every military figure of standing that Isis cannot be defeated solely from the air.
The Prime Minister has said that there are forces in the area already capable of taking on an Isis weakened by the bombing campaign, but this claim has been met with considerable scepticism.
Syria is a political tinderbox, with Russia pursuing a different agenda from the West. Getting any consensus on the way ahead will be mightily difficult.
A ground force drawn from the Arab nations in the area would be the preferred option to follow up on the bombing campaign, but it will take unparalleled diplomacy to achieve that outcome.
The concern of many people is that last night's vote could be the start of even deeper involvement, culminating in British troops marching into battle again in the Middle East.
That is where the public would probably draw a line in the sand.
Even the Northern Ireland MPs who voted with the Government last night don't want to see Ulster boots on the ground in Syria or Iraq.