IT IS something of a sad irony that the very week after the long-anticipated Chilcot report highlighted the worrying extent of groupthink in Whitehall and Westminster, large numbers of MPs will trip through the Westminster lobbies to support in principle the idea of renewing a Continuous at Sea Deterrent that represents a 20th-century solution to our increasingly 21st-century problems.

The Defence Select Committee, of which I am a member, has recently completed an inquiry into the implications of increased Russian assertiveness for UK security and in evidence session after evidence session I struggled to find evidence that would support the renewal of Trident at a cost of up to £205 billion.

In fact, as witness after witness listed the the very real 21st-century threats faced by the UK and our Nato and EU allies, almost all could very much be filed under the heading of "hybrid warfare": actions which are specifically targeted to ensure a prompt response is impossible.

Think of the "little green men" who invaded and held Crimea. With no identifying markings and official denials from the Kremlin it had anything to do with them. The same is seen in the "self-defence forces" which have sprung up in Eastern Ukraine – by the time the identity of the belligerents is established, it is too late to take action.

Closer to home as well, as we see an increase in Russian naval and air activities in our own territory, the pattern is similar: no outright aggression but a determination to poke and prod and test reaction times, which from the UK have often been laughably slow. The last time the Russian Carrier Admiral Kuznetzov "took shelter" in Scottish waters, it took 24 hours for a frigate to arrive from Portsmouth to escort it from the Moray Firth.

When myself and SNP colleagues visited NATO HQ in Brussels last month, we heard much about the consequences of Brexit for European security, but we didn’t hear anything about nuclear weapons: that is because, as an independent nuclear deterrent, Trident is the very antithesis of alliance solidarity.

We also heard lots about the need for NATO to improve and increase its conventional forces, particularly to be able to respond to these hybrid threats. Indeed, the most prominent commitment to emerge from the Warsaw Summit last week was for a multinational brigade to be placed in the Baltic States and Poland – something we supported wholeheartedly – a principle referred to by many as "modern deterrence" and something which Trident resolutely is not.

The UK’s NATO allies would rather it focused on its most basic of tasks, namely protecting UK territory, and that of its neighbourhood. When that Russian Carrier group called, it was doing so because it knew there were no major surface warships based in Scotland, and indeed none based north of the Channel, a situation which underlines Westminster governments’ obsession with protecting the UK’s status as a nuclear power, ahead of protecting UK territory.

The Royal Navy is now reduced to only 17 usable frigates and destroyers: to put that into context, the taskforce which retook the Falklands in 1982 had more than 40. The Falklands itself is currently without major warship protection for the first time since that conflict, and UK anti-piracy and people-smuggling operations in the Mediterranean and Caribbean are frequently undertaken by vessels that are not suitable for the task. Put simply, Trident is eating into our conventional budget.

This is where we get to the key point on Trident’s military futility, since the cost of Trident was reassigned to the Ministry of Defence budget, every penny spent on Trident is now a penny less spent on conventional defence. Hardly any surprise that a former Sea Lord to the defence committee recently told the committee the Navy had "run out of money" to support the Type 26 programme.

So, while the entire Successor program has its funds ring-fenced, with added generous contingencies, projects like the Type 26 frigates due to be built on the Clyde, face delay after delay, with a knock-on effect on the construction, effecting jobs and the skills of the workforce.

And so it is, on Monday I will get to my feet in the Chamber and remind this Tory Government, and their Labour helpers, of that salient fact, in hope rather than expectation that they will think for themselves and focus on real capability rather than expensive vanity projects such as Trident.

SNP MP Douglas Chapman is a member of the House of Commons Defence Select Committee.