And they have to have an idea of an endgame out of this dangerous place and towards safer ground.
Whatever Russian leader Vladimir Putin's perceived historical grievances over the break-up of the Soviet Union and Nato expansion, his regime's invasion of neighbour Ukraine has rightly caused mass revulsion, anger and disgust. There have been air attacks, hospitals bombed and hundreds of civilians killed.
War is bad for Ukraine with people trapped if they haven't fled their bombarded cities to bordering countries already. It is bad for Russia which has stepped into military territory that could become quicksand, as its economy and political standing is being battered. And it's bad for other countries to have to quickly respond while anticipating deep financial fallout and buying time to improve their defences.
This has happened in a frenetic, feverish atmosphere similar to the post-September 11 period, although the echoes here in people's emotional reactions go back to World War II.
At present, there is a narrow window for a ceasefire, deal, and withdrawal of troops to take place - before a longer-term calamity settles in instead.
An agreement would be by far the best outcome for civilians, seeing with horror for themselves how thin the skin can be between normal and uncivilised life. It would also be better for the Russian soldiers, who by various estimates are taking heavy losses.
But countries are also making calculations about the future: military budgets and alliances; whether Putin's regime should be brought to its knees; how to bolster Ukraine militarily and economically; how to avoid a direct clash between nuclear powers, and how to accelerate a move away from fossil fuel dependency.
In this situation, bold changes tend to be cheered while more cautious moves or background co-ordination are less understood or appreciated.
Western countries are probably lucky to have someone of United States President Joe Biden's experience in the White House during this crisis.
He has been clear that Ukraine is being supported but within defined limits - including US$14 billion in aid but no US ground troops - in order to prevent World War III. It would be up to Putin to trip that wire of taking on Nato directly.
Biden has so far organised a unified response to Putin through the European Union and Nato. That response has made it clear who is at fault in this war, swiftly introduced economic punishment and avoided military escalation outside non-Nato member Ukraine. When Putin has talked up Russia's nuclear capability, the US has not match the rhetoric.
Biden and other leaders have been correct to reject the idea of a no-fly-zone over Ukraine. It would involve Nato forces destroying Russian air defence systems and likely being drawn into direct combat with Russian forces. A suggestion by Poland to send Ukraine its MiG-29 fighter jets via a US airbase in Germany was more messily handled among the allies but again showed an attempt to avoid escalation.
One of the key lessons of the Iraq conflict was how badly escalation can go wrong, to the tune of tens of thousands of lives lost, billions of dollars spent and countries laid waste.
Here, Putin is being given a clear message: Pull out soon or face an insurgency of attrition in Ukraine, well supplied with Western weapons.
The Ukrainians have been successful at slowing the Russian military's progress with anti-tank and anti-aircraft weapons. But the Russian forces have made headway to occupy more Ukrainian land in the east and southeast near Odessa. A loss of that port would threaten Ukrainian access to the Black Sea. The wretched prospect of Kyiv being encircled is edging closer.
What Putin has done is clearly notify his neighbours of the threat he poses. Western Europe is now wide-awake to that.
