A chilling message from Russia's shelling at a Ukrainian nuclear power plant is that this war may have few boundaries.
It has already resulted in mind-spinning geopolitical changes, and stepped up aggression on Ukrainian cities in a week and a half. Further escalation is possible and there's both predictable and unpredictable consequences with that.
For instance, no-one knows yet what the political fallout could be from the intense economic pressure and isolation being applied to Russia - both its Kremlin-friendly oligarchs and its citizens. Or where President Vladimir Putin's nuclear sabre-rattling will lead.
The attack on the Zaporizhzhia plant on Friday was a triggering event for anyone who remembers the 1980s and the Chernobyl disaster. In the end, the IAEA said that a Russian weapon hit a training centre, not a reactor at the plant. This extremely reckless action raised the spectre of a potential release of radiation at some stage of the conflict.
At present, Nato countries are supplying Ukraine with weapons and aircraft, while increasing troop numbers and conducting air patrols along the alliance's edge.
The nuclear plant incident gave Ukrainian President Volodymyr Zelensky an opportunity to argue that Nato should also bring in a no-fly-zone over his country. He said a nuclear explosion would be "the end for everyone. The end for Europe. The evacuation of Europe."
But there is no appetite for a no-fly-zone against a nuclear power at the White House, where President Joe Biden has ruled out US combat troops in Ukraine, or among European allies.
Nato Secretary-General Jens Stoltenberg cited the risk of wider war, saying that to enforce it, Russian planes would have to be shot down. So far Russia has mainly used artillery and missiles rather than air power.
From Zelenskiy's perspective, a Western-backed urban insurgency against Moscow would take time to be effective and already photographs of Ukrainian cities recall haunting scenes of previous Russian war campaigns in Aleppo, Syria, and Grozny, Chechnya.
He said: "The alliance has given the green light to the bombing of Ukrainian cities and villages by refusing to create a no-fly zone".
It's a tricky balancing act for Nato, attempting to keep the conflict contained to within Ukraine's borders, while trying to avoid direct involvement and confrontation with Russia as its countries send planes, anti-tank missiles, anti-aircraft missiles and drones to Ukraine.
Preventing the fighting from spreading westwards could potentially give Putin an off-ramp out with a diplomatic deal, cutting the conflict shorter than what it could be. Initial attempts at talks, evacuations and ceasefires haven't worked.
It appears already that conquering and then occupying Ukraine would be very difficult for the Kremlin, as well as being economically and politically ruinous for Russia itself.
Nato, which had seemed to be struggling for relevance, has been revived. Even independent-minded countries such as Turkey, Switzerland and Hungary have picked the side against Russia.
As the conflict becomes a deeper hole for Russia, the dangers of greater destruction, a wider disaster, mistakes and miscalculations grow.
The longer the war goes on and the greater the pressure builds on a cornered Putin, the more the narrative grows that his own future is on the line. That the only way Russia rehabilitates itself in the world is by having a different leader at the helm.
That adds greatly to the uncertainty over what happens next.