Britain and France on Friday agreed to speed up plans to create a joint control and command center for future military operations.
British Prime Minister David Cameron said after a UK-France Summit in Paris that the deal was "a real breakthrough" which would "make a big difference to the military capabilities of both Britain and France."
Cameron and French President Nicolas Sarkozy also agreed to go ahead with the next phase of plans to build a new generation of an unmanned "fighter drone" aircraft.
Co-operation over civil nuclear energy, which the UK government says will create several commercial deals worth more than £500 million, was another outcome of the summit.
Cameron is meeting Sarkozy for the first time since their bitter clashes over the Eurozone debt crisis. They are also expected to seek new deals between British and French companies to build aircraft and nuclear power stations.
Speaking at a joint press conference after the talks, Cameron said their relationship was "easily strong enough to survive the odd bump and bounce when we have a disagreement. That's what politicians do. That's what friends do," he said, adding that the UK and France were closer now than at any time since World War II.
Sarkozy praised Cameron for his role in Libya, calling him "a very brave man," and added that "perhaps, had I been in David Cameron's position, I would have defended British interests in exactly the same manner he has."
Both the countries will work together with the International Atomic Energy Agency (IAEA) "to strengthen international capability to react to nuclear emergencies and establish a joint framework for cooperation and exchanging good practice on civil nuclear security."
The move comes 11 months after a tsunami in Japan wrecked the Fukushima Daiichi nuclear power plant, leaking radioactive material into the air and sea.
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