Military chiefs, civil servant and politicians are not always ready or equipped to fight the combats in front of them, let alone the wars of the future.
Think of Iraq and Afghanistan – their crystal ball is often as muddy as yours or mine.
While the 2010 Strategic Defence& Security Review( SDSR) did identify terrorism and international military crisis as high level( tier 1) threats, there was no specific mention of Russia and so-called Islamic State( IS) did not exist in anything like its present form.
The 2015 SDSR will identify both IS and Russia as tier 1 threats, but they are not able to be the same menace five years hence.
They say that armies develop to fight the last war they fought and military plans don’t survive the first contact with the foe.
“In 2010 it was rather assumed the armed forces would get out of Afghanistan and take a bit of a breather, ” says Michael Clarke, director of the defence think tank Rusi.
Instead “the world has shown us the armed forces won’t be getting a holiday, ” he says.
First, the government should be commended on its commitment to carry out a defence review every five years. Before, defense reviews were done ad hoc.
But ministers will still have to overcome a high degree of scepticism as to whether this latest SDSR is genuinely “strategic” or if it matches Britain’s global ambitions with the resources required.
SDSR 2010 may have been strategic in name but it’ll be remembered for the savage cuts that followed.
It wasn’t just the scrapping of iconic names, it left gaping pits in Britain’s defenses – with no aircraft carriers for the Royal Navy and no maritime patrol aircraft to hunt down Russian submarines.
Strategic Defence& Security Review: What happened last time
David Cameron announced that Harrier jump planes, the Navy’s flagship HMS Ark Royal and schemed Nimrod spy airliners were to be axed 42,000 MoD and armed forces jobs were to go by 2015 The RAF and Navy were to lose 5,000 chores each, the Army 7,000 and the MoD 25,000 civilian staff Overall, defence spending was to fall by 8% over four years Mr Cameron denied it was a cost-cutting exert and said the UK had to be “more thoughtful, more strategic and more co-ordinated in the way we advance our interests and protect our national security” Image caption Image caption