• Nato has no role in Iraq, or Ukraine • But Nato leader uses Putin in attempt to shake up western alliance

The greatest security threat to Britain, and other western countries, comes from militant Islamists in Iraq and Syria, according to governments in the west. Yet the world's most powerful military alliance can do nothing about it.

That truth is becoming increasingly evident every day. Thursday was no exception, as Anders Fogh Rasmussen, Nato's general secretary, made clear just how desperate a state the 28-nation western alliance is in. He stressed the danger posed by Vladimir Putin rather than the brutal groups fighting in the Middle East.

Two former British chiefs of defence, made it quite clear what they thought in evidence to the House of Commons defence committee on Wednesday.

Asked what he thought were the biggest threats facing the UK and its allies, Lord Stirrup described the danger of Middle East boundaries drawn up during the first world war unravelling, and the rise of China, as "major strategic shifts". What was happening in Ukraine was less significant, he said.

Lord Richards, who retired as Britain's defence chief last year, was more forthright. When MPs on the Commons defence committee,asked him about the greatest threat facing Britain's security, Richards replied: " What I've been saying for years - militant jihadism and non-state actors".

It was a "massive problem", he continued, that needed a "global response".

Asked about Ukraine, Richards replied: "What drives Russia is the protection of her vital national interest. Crimea was always going to remain Russian, he went on, saying it was gifted to Ukraine by "sleight of hand" - a reference to the decision in 1954 by the Ukrainian-born Soviet leader, Nikita Khrushchev, to transfer Crimea to Ukraine as a "symbolic gesture".

Putin's action on Crimea was "entirely predictable", said Richards.

He said what was needed now was Russia to join in the fight against jihadists.

Rasmussen's emphasis, unsurprisingly, was rather different. He dwelt at length, in a speech top the Chatham House thinktank, entitled The Future of Nato: A Strong Alliance in an Unpredictable World, on what he called Russia's attempt to "re-write international rules", and "illegal military actions" in Ukraine and Crimea.

Asked whether Nato would intervene in Iraq, Rasmussen could only say he strongly condemned the violence there. If Russia intervened further in Ukraine (not a member of Nato) then that would be a "very regrettable step backwards", replied the Nato secretary general.

What he called the "international community" would have to respond "in a strong manner". He mentioned "deeper economic sanctions, to isolate Russian internationally".

• David Cameron, meanwhile, says the west must adopt a policy of "intelligent" intervention in Iraq. Sadly, he appears to have decided to go for broke in his intervention over who should be the next head of the European commission, going down fighting in his bid to stop the candidature of Jean-Claude Juncker, the former Luxembourg premier, who is backed, among others, by the German chancellor, Angela Merkel.

The row is scheduled to be on the agenda of an EU summit on Friday, in of all places in this centenary year of the start of the first world war, Ypres.