Brexit aside, we are suddenly facing the biggest foreign policy crisis since the Falklands. Attempted murder in Salisbury constitutes a warlike act says Tom Tugendhat, respected chairman of the Commons foreign affairs committee.  The Daily Telegraph quotes this in its leader headline: “Warlike act to which NATO must respond”, and political, public and media opinion broadly agree.

So, how bad could this get?  What must we do now?  What should we be prepared to do if things get even worse?  What is Putin likely to do next? How will he respond?  What unintended consequences might follow?

How bad could this get?  Pretty bad.  It looks like Putin has capped a run of aggression in Europe and Syria with a state-sponsored brazen attack – using hideous banned chemical weapons – on one of Europe and the West’s most important nations.  Not to mention, a fellow united nations security council member.  Putin is the most powerful autocrat in the world.  He will deny everything. He does not compromise or keep to his word. He has a macho streak and will likely retaliate to whatever responses we deploy.

So, what must we do now?  Top priority is to prevent further attacks against the UK and its citizens, and in the process help safeguard others.  This means a very firm but proportionate mix of overt and covert responses. Overt measures should include: sanctioning oligarchs and a wider net of Russians who aid and abet Putin, along with those living in UK who cannot satisfactorily explain their wealth; getting NATO and EU allies on board for effective collective action and ‘red line’ warnings, and using united nations and international weapon treaty fora to shine the light on every bit of Russian bad behaviour.

What should we be prepared to do? We will need to upgrade our warning and intelligence and various military and civilian response capabilities, focusing on unconventional weapons, cyber, digital, and information operations. Beyond prudent national defence, we have a huge leadership role to play in getting the West, and NATO in particular, to develop a full scale holistic strategy and demonstrate collective resolve. Defence spending will have to go up, as will spending on soft power projection.  Strategic planners now refer to ‘full-spectrum information and culture war’ and this domain may well become the critical and defining battle space.

What is Putin likely to do next?  Putin will continue to deny, obfuscate and exploit opportunities and divisions within the West.  He will not hesitate to use almost any tool and tactic that he can get away with.  We should stand by for more fake news, false information, and cyber-attacks.  His re-election and genuine broad support at home will embolden him further.  He has not blinked invading territories in Europe, nor enabling carnage in Syria.  We should prepare for things to get worse before they get better.

What other impacts might we see?  History is full of irony.  Notwithstanding that as Home Secretary Theresa May could and should have been tougher on Russia, Putin may give the PM her Thatcher hand bag moment.  The world is looking on intently.  US leadership is uncertain and distracted, and Germany shows no sign of getting off both back feet.  It may be ‘here we go again’ time.

It is time for UK to garner the moral courage and take a lead for Europe.  Despite mistaken defence cuts, we are still the top European NATO power and most European allies look to us in dangerous times. Further irony – play this right, Mrs May, and it will reinforce the prospects for a sensible mutual Brexit settlement.

Nigel Hall is a Visiting Senior Research Fellow at King’s College London