Britain and France vowed to work hand-in-glove Tuesday as their leaders ushered in an unprecedented era of defense cooperation by agreeing to create a joint force and share nuclear test facilities.
British Prime Minister David Cameron and French President Nicolas Sarkozy inked two treaties which they say will allow both nations to remain global players while cutting defence budgets following the financial crisis.
The two neighbors historic rivals for centuries who fell out spectacularly over the 2003 Iraq invasion insisted the pact will not deprive their militaries of the ability to act independently.
"Today we open a new chapter in a long history of cooperation on defense and security between Britain and France," Cameron told a joint press conference following the signing ceremony, backed by the French and British flags.
Sarkozy, speaking through an official translator, said the deal was "historic" and "unprecedented".
"France and Britain's clocks strike at the same hour at the same time," he told a press conference. "We intend to work hand in glove."
The deal includes a joint rapid reaction force of up to 5,000 troops deployable from next year; plans to share nuclear testing equipment by 2015; and the use of aircraft carriers from about 2020.
The pact puts an end to centuries of rivalry from the invasion of England by the French-speaking Normans in 1066 through to 14th and 15th century battles for control of France and the Battle of Waterloo in 1815.
Cameron said the two countries were "natural partners" but added: "Britain and France are and will always remain sovereign nations able to deploy our armed forces independently."
He also said alleged Al-Qaeda parcel bombs sent from Yemen and discovered on US-bound flights last week "have reminded us that our societies and our security have never been more connected."
The first treaty covers a wide agreement on defense, from the creation of a new combined joint expeditionary force to sharing the use of aircraft carriers, the maintenance of transport planes and some joint procurement.
The new force will begin training next year and would be deployed on an ad hoc basis under a single commander, likely speaking English.
The two countries will also share the use of their aircraft carriers from 2020. With each country operating only one carrier, they will be able to use the other nation's vessel when theirs is under maintenance.
Cooperation is also planned on the new A400M transport aircraft they are both buying, with plans under way to share maintenance and training.
The second treaty will cover plans to share technology in the testing of nuclear weapons, although officials stressed this would not see the two countries share nuclear secrets, nor the codes to their nuclear submarines.
Under the nuclear deal, Paris and London will test the safety of their nuclear arsenals in a joint facility in France, according to the French presidency.
A nuclear simulation centre will be built at Valduc, eastern France, which will work with a French-British research site in Aldermaston, southern England. Several dozen French and British experts will work on the project.
The British and French already work alongside each other in NATO operations and 12 years ago British premier Tony Blair and French president Jacques Chirac hailed their intention to cooperate on defence issues.
However, little came of it and the pair disagreed over the war in Iraq, which emphasised Britain's focus at that point on US, rather than EU, relations.