Germany will need up to 60,000 additional troops under new NATO targets for weapons and personnel, Defence Minister Boris Pistorius said on Thursday, as the alliance beefs up its forces to respond to what it sees as an increased threat by Russia. "We are stepping up to our responsibility as Europe's largest economy," the minister told reporters ahead of a meeting with his NATO counterparts in Brussels that was set to approve the new targets.

The fresh demands are tailored to the alliance's defence plans, thousands of pages of secret documents drawn up for the first time since the end of the Cold War, that detail how allied forces would respond to a Russian attack on NATO.

Translating these plans into the military tools needed, NATO found severe shortfalls in various areas - ranging from large formations of combat-ready ground troops to long-range weapons, sufficient ammunition stockpiles and secure communications.

Pointing to the secret nature of the targets, NATO chief Mark Rutte only gave a rough outline of the gaps the alliance seeks to plug.

"We have to invest in our air defence systems, we have to invest in our long-range missiles, we have to invest in our maneuverable land-formations, command and control systems - all of this has to happen," he told reporters, adding that all this would require huge investments. HUGE CHALLENGE FOR BERLIN In total, the Bundeswehr, Germany's armed forces, will need roughly 50,000 to 60,000 additional active soldiers over all branches of the military, according to Pistorius, which would put the future strength of the German forces at between 250,000 and 260,000 troops.

Last week, Reuters reported that NATO will ask Germany to provide seven more army brigades alone, or some 40,000 troops. Sources, who all spoke on condition of anonymity, put the target for the total number of brigades that NATO allies will have to provide in future to between 120 and 130.

Recruiting tens of thousands of extra troops will be a big challenge for Berlin, however, and likely spark a fresh debate on whether conscription - suspended in 2011 - should be reintroduced.

The Bundeswehr has not yet met a target of 203,000 troops set in 2018, and is currently short-staffed by some 20,000 regular troops, according to defence ministry data.

Pistorius said the government would be faced with the question whether the voluntary military service it aims to introduce will be sufficient to fill the Bundeswehr's ranks.

Still, he warned that the military currently could not absorb a bigger number of conscripts due to a lack of barracks and trainers.

"Until we have such capacities, we'll have a voluntary service - and maybe beyond that if we are an attractive employer and win enough young men and women for the military who agree to serve for a longer time."

In a major shift, Germany recently loosened its debt brake to enable a surge in defence and backed Rutte's plan to hike NATO's spending target to 5% of GDP.