British troops and strike aircraft are to be based in the Gulf as part of the most significant new deployment of UK armed forces since Afghanistan.

The return to "east of Suez" was signalled by General Sir David Richards in the chief of defence staff's annual Christmas lecture at the Royal United Services Institute in London on Monday evening.

His speech was highly significant. It follows from what the Obama administration has been telling the Europeans — they have got to take more responsibility looking after the security interests not only of their own continent but those in the Middle East and Gulf.

And it reflects David Cameron's view that British interests — not least commercial ones, and arms sales in particular — lie among the emirates, sultanates, and kingdoms, of the Gulf.

These states are concerned about Iran, and will be for the forseeable future whatever that country's nuclear ambitions.

This is how Richards put it: "Though more conceptual work is needed, given the importance of the region and clear prime ministerial intent, I envisage two or more adaptable brigades forming close tactical level relationships with particular countries in the Gulf and Jordan, for example, allowing for better cooperation with their forces".

Richards added: "Should the need arise for another Libya-style operation, we will be prepared. This would greatly enhance our ability to support allies as they contain and deter threats and, with our naval presence in Bahrain, air elements in the UAE and Qatar, and traditional but potentially enhanced roles in Oman, Kuwait and Saudi Arabia, would make us a regional ally across the spectrum".

British defence chiefs are holding out the prospects of British barracks in Bahrain (already a Royal Navy as well as US navy base) quarters in Qatar, and Typhoon hangars on the air bases of the UAE (which are toying with the idea of buy some Typhoons for themselves).

The Gulf was not the only region Richards mentioned. In Africa, he said, British army brigades "would be tasked to support key allies in the east, west and south whilst another might be given an Indian Ocean and SE Asian focus, allowing for much greater involvement in the FPDA (Five Power Defence Arrangements between the UK, Australia, New Zealand, Malaysia and Singapore) for example".

Against the background of America's "pivot" to the Pacific, this all sounds like another step towards the end of Nato, an alliance based on an area, the North Atlantic, which no longer has anything like the strategic significance it once did.

In his wide-ranging speech, Richards talked about deterrence, Britain's new Joint Expeditionary Force, cyber attacks, the dangers of divorcing soft and hard power, and How We Will Fight, which will be a kind of mission statement for Britain's armed forces.

He went through the inventory of kit available to the navy, army, and airforce.

He praised the potential of Britain's two new aircraft carriers — about which there is still much private scepticism in military circles — but made it clear, as he has done before, that the navy needs "more vessels tailored to discrete but important tasks, to be deployed on a range of routine non-warfighting duties".

This was a thinly-disguised reference to anti-piracy and other operations against "unconventional" or "non-state" enemies.

Noticeable by its absence of any mention was Britain's fleet of Trident ballistic missile submarines armed with nuclear weapons. It is Britain's most powerful weapon, a product of the cold war. It should also be Britain's most controversial weapon.

The Conservatives want to replace it with a "like for like" system. There is widespread but suppressed opposition among defence chiefs to its replacement. But they say it is an entirely "political" decision. Therefore they cannot even mention it in public.