BRUSSELS - Anders Fogh Rasmussen started work on Monday as NATO's new secretary-general, part of a team assembled by President Barack Obama to lead the war effort in Afghanistan.

Fogh Rasmussen, the former Danish prime minister, was greeted by the alliance's top civilian and military leaders as he arrived at NATO headquarters.

His predecessor, Jaap de Hoop Scheffer, has repeatedly warned that the war in Afghanistan represents a crucial test of the power and relevance of the 60-year-old alliance.

NATO has about 64,000 soldiers in Afghanistan -- half of them Americans -- where they are struggling to contain a rising Taliban insurgency. More than 20,000 new U.S. troops are being deployed to the theatre, but European allies have been reluctant to increase their contributions to the international force.

Fogh Rasmussen is due to outline his priorities later Monday, including naming a panel to draft NATO's new strategic concept, which reflect NATO's new role outside Europe, its traditional area of focus.

Madeline Albright, the former U.S. secretary of state, will likely be on the panel, officials said.

Alliance leaders picked Fogh Rasmussen during their summit in April. The Dane was a controversial choice because he infuriated many Muslims following the 2005 publication in Denmark of 12 cartoons of the Prophet Muhammad.

As prime minister, Fogh Rasmussen distanced himself from the cartoons but resisted calls to apologize for them, citing freedom of speech and saying his government could not be held responsible for the actions of Denmark's media.

Obama has announced a new war strategy boosting the number of U.S. ground troops and helping train Afghan security forces. He has appointed several new commanders to key posts, including Adm. James Stavridis as NATO's commander and Gen. Stanley McChrystal as its U.S. commander in Afghanistan.

A possible source of additional European troops could be NATO's 14,000-strong contingent in Kosovo, the site of war 10 years ago. Relations with Serbia have been normalized since then, and one of Fogh Rasmussen's duties will be to reduce the peacekeeping force there by up to 10,000 soldiers over the next year.

Fogh Rasmussen will also work on the alliance's evolving anti-piracy mission off the coast of Somalia, the issue of NATO expansion and tricky relations with a resurgent Russia.

Ties between NATO and Moscow have improved significantly since they were frozen after the Russia-Georgia war a year ago, but Russia still objects to plans to eventually bring Ukraine and Georgia into the alliance.