I was in the British Foreign and Commonwealth Office for over 20 years and a member of its senior management structure for six years, I served in five countries and took part in 13 formal international negotiations, including the UN Convention of the Law of the Sea and a whole series of maritime boundary treaties. I headed the FCO section of a multidepartmental organisation monitoring the arms embargo on Iraq.

I am an instinctively friendly, open but unassuming person who always found it easy to get on with people, I think because I make fun of myself a lot. I have in consequence a great many friends among ex-colleagues in both British and foregin diplomatic services, security services and militaries.

I lost very few friends when I left the FCO over torture and rendition. In fact I seemed to gain several degrees of warmth with a great many acquantances still on the inside. And I have become known as a reliable outlet for grumbles, who as an ex-insider knows how to handle a discreet and unintercepted conversation.

What I was being told last night was very interesting indeed. NATO HQ in Brussels is today a very unhappy place. There is a strong understanding among the various national militaries that an attack by Israel on a NATO member flagged ship in international waters is an event to which NATO is obliged - legally obliged, as a matter of treaty - to react.

I must be plain - nobody wants or expects military action against Israel. But there is an uneasy recognition that in theory that ought to be on the table, and that NATO is obliged to do something robust to defend Turkey.

Mutual military support of each other is the entire raison d'etre of NATO. You must also remember that to the NATO military the freedom of the high seas guaranteed by the UN Convention on the Law of the Sea is a vital alliance interest which officers have been conditioned to uphold their whole career.

That is why Turkey was extremely shrewd in reacting immediately to the Israeli attack by calling an emergency NATO meeting. It is why, after the appalling US reaction to the attack with its refusal to name Israel, President Obama has now made a point of phoning President Erdogan to condole.

But the unhappiness in NATO HQ runs much deeper than that, I spoke separately to two friends there, from two different nations. One of them said NATO HQ was "a very unhappy place". The other described the situation as "Tense - much more strained than at the invasion of Iraq".

Why? There is a tendency of outsiders to regard the senior workings of governments and international organisations as monolithic. In fact there are plenty of highly intelligent - and competitive - people and diverse interests involved.

There are already deep misgivings, especially amongst the military, over the Afghan mission. There is no sign of a diminution in Afghan resistance attacks and no evidence of a clear gameplan. The military are not stupid and they can see that the Karzai government is deeply corrupt and the Afghan "national" army comprised almost exclusively of tribal enemies of the Pashtuns.

You might be surprised by just how high in Nato scepticism runs at the line that in some way occupying Afghanistan helps protect the west, as opposed to stoking dangerous Islamic anger worldwide.

So this is what is causing frost and stress inside NATO. The organisation is tied up in a massive, expensive and ill-defined mission in Afghanistan that many whisper is counter-productive in terms of the alliance aim of mutual defence. Every European military is facing financial problems as a public deficit financing crisis sweeps the continent. The only glue holding the Afghan mission together is loyalty to and support for the United States.

But what kind of mutual support organisation is NATO when members must make decades long commitments, at huge expense and some loss of life, to support the Unted States, but cannot make even a gesture to support Turkey when Turkey is attacked by a non-member?

Even the Eastern Europeans have not been backing the US line on the Israeli attack. The atmosphere in NATO on the issue has been very much the US against the rest, with the US attitude inside NATO described to me by a senior NATO officer as "amazingly arrogant - they don't seem to think it matters what anybody else thinks".

Therefore what is troubling the hearts and souls of non-Americans in NATO HQ is this fundamental question. Is NATO genuinely a mutual defence organisation, or is it just an instrument to carry out US foreign policy? With its unthinking defence of Israel and military occupation of Afghanistan, is US foreign policy really defending Europe, or is it making the World less safe by causing Islamic militancy?

I leave the last word to one of the senior NATO officers - who incidentally is not British:
"Nobody but the Americans doubts the US position on the Gaza attack is wrong and insensitve. But everyone already quietly thought the same about wider American policy. This incident has allowed people to start saying that now privately to each other."