BERLIN (AFP) - Germany's Defence Minister said Tuesday that Berlin would resist any US pressure to send troops to the strife-wracked south of Afghanistan, keeping its focus on the calmer north of the country. "It remains the case that our task is to stabilise the north. And this will also be the case in future," Franz Josef Jung said in an interview on ARD public television. Jung said the vast area patrolled by German troops in northern Afghanistan was half the size of Germany and that Berlin was also providing back-up support for other forces in the region. "We are the third largest troop provider," the Minister noted. In Berlin, German Chancellor Angela Merkel called on Nato to revamp its security strategy with a stronger focus on disarmament and development and urged US president-elect Barack Obama to join the drive. She told a security conference that Nato, on the eve of its 60th anniversary next April, needed to take a broader approach to security that did not view military and civilian cooperation, such as in Afghanistan, at odds. "I consider it necessary to commission a new strategic concept" at an anniversary summit on the Franco-German border in April, she said. Merkel said Nato had developed its security strategy before international terrorism had reshaped the challenges facing the alliance, and now needed an "interlinked security policy" bringing together more than troop deployments. The German leader said Nato's International Security Assistance Force (Isaf) in Afghanistan was a clear example of the gains that could be made in security by developing civilian infrastructure as well as fighting militants. But she sharply rejected calls in Germany to set a time limit on the deployment of its troops in the country, saying they should stay until Afghanistan "can stand on its own two feet." In London, British Defence Secretary John Hutton compared the conflict in Afghanistan to World War I Tuesday as Europe marked the 90th anniversary of the conflict's end. Hutton said both conflicts were fought to defend a "vital national interest" and likened the bravery of British troops fighting as part of the Nato-led coalition in Afghanistan to that of World War I veterans. "In both 20th century world wars, Britain fought because we needed to defend our vital national interest. The same applies today," he said during a speech at the International Institute for Strategic Studies think-tank in London. "In Afghanistan, the deployment of our armed forces was in response to an attack on our national interests every bit as unambiguous as the threat presented by the invasions of Belgium in 1914 or Poland in 1939." Meanwhile, British Prime Minister Gordon Brown on Tuesday said his country would consider sending more troops to Afghanistan in a change of strategy sought by Barack Obama, but other countries must help share the burden. He made the comments when asked if Britain would comply with a request by US president-elect Obama for more troops as part of a switch of focus from Iraq to Afghanistan, where Britain has over 8,000 soldiers already. "Of course we're ready to consider what's necessary, but it must be part of a burden-sharing exercise," he said, responding to a question at the monthly Press conference in his Downing Street office in London. Britain has added more troops in the last few weeks, and has now the second largest force there after the United States, he said. Most are based in southern Afghanistan, and more than 120 have been killed.