We might kill or disrupt ISIS terrorists plotting atrocities against our citizens by bombing targets in Syria, just as we might be able to snatch them and then quiz them in Iraq by deploying special forces (or, if this is already taking place, by sending in more of them). There is a case for doing so.  But however many targets we pulverise or terrorists we question, ISIS will still be able to hold some of its ground, at least.  And for as long as it holds territory it will continue to pose a threat to British interests and lives.

There are thus three options open to the Government, at least on paper.  First, send in ground troops to Syria and Iraq as part of an international plan.  Second, carry on the present air strikes in Iraq, presumably at the same rate.  (We have hit about 130 ISIS targets.  The Americans have hit roughly 7500.)  Third, extend the strikes and other military action to Syria – and run the risk of them being seen to be ineffective if further massacres of British citizens take place, here or abroad, which in turn would stir calls for further air strikes…which might not prevent the further loss of British civilian lives…

The first option is not going to happen.  The second is the most likely to take place – given the size of the Government’s majority, the unreliability of Labour and the doubts of Conservative backbenchers about option three.  The latter will ask the same question about it as they did of the Commons Syria vote two summers ago, namely: what happens next?

Then, they wanted to know what would happen if we bombed targets controlled by the Assad regime, but it continued the chemical weapons attacks these were meant to deter.  Now, they want to know what the consequences would be were the Government to up the strikes, but further atrocities against British citizens to then take place.

All this points to how uncertain the Government’s knowledge – and indeed strategy – is.  ConservativeHome opposed the proposed strikes in Syria on the ground that there was a risk of being drawn in to its civil war to no productive end.  At the time, I was rung rung by a senior Minister who argued passionately that Assad was a despot who Britain should confront.  A year later, the very same Minister went public to claim that Assad was an ally in the battle against ISIS. And remember: we don’t know whether or not the Tunisian atrocity was planned in Syria in the first place.

Upping the number of air strikes in Iraq or carrying them over into Syria might make some voters feel better – that “something is being done”.  And it doubtless could be done without committing to the two per cent NATO minimum, which Ministers might find useful (though some believe that, in the wake of Tunisia,  George Osborne may commit to the target in next week’s Budget – which would be excellent news).  But something-must-be-donery is seldom a solid basis for a policy, if ever.

The lesson of last week is stark.  We like to feel that we are safe from terror attacks if we jet off to other countries for a beach holiday, or for other reasons.  But we are not.  David Cameron will not send in gunboats, Lord Palmerston-style, to protect us: we are beyond the Government’s jurisdiction.  Here at home, it is different.  Ministers are responsible for stopping ISIS and Al Qaeda terror attacks on our own soil.  The security forces claim that about 40 have been thwarted over the last decade.

Which takes us to the essentials.  Most British Muslims oppose violent Islamism.  But even one “lone wolf” from among their 2.5 million number could create carnage.  And the evidence to date is that fewer terror attacks have been carried out by lone wolves – such as Roshonara Choudhry, the woman who stabbed Stephen Timms in his surgery – than by people on the security services’ radar, such as Mohammed Siddique Khan, one of the 7/7 bombers, and Michael Adebolajo, one of Lee Rigby’s killers.

We need bomb strikes in Syria less than better border control here.  We need to switch more resources to home security.  We need an army, so to speak, of spies and informers.