"Sharing nuclear weapons is an issue we need to discuss... We have to become stronger together in our nuclear deterrence," Merz said in an interview on Deutschlandfunk radio, a day after reaching an agreement on the basic principles for a coalition between his conservative party and the Social Democrats (SPD).

"We should discuss with both countries (France and Britain), from the perspective of complementing the US nuclear shield, which we of course still want to maintain," he stressed.

During World War II, Germany pledged not to develop nuclear weapons under many international treaties but still participated in NATO arms-sharing agreements.

At a summit in Brussels on Thursday, EU leaders backed plans to increase defense spending amid concerns that Russia, following its military campaign in Ukraine, could attack an EU country and that Europe could not fully rely on the United States for protection.

Mr Merz's tougher stance on security and migration reflects a shift in Germany's political landscape, as the far-right AfD party has risen to become the country's second-largest party.

Mr Merz aims to form a coalition government before Easter and has pledged to push the current parliament through two major financial packages on infrastructure and defence.

Cao Phong (according to Reuters, AJ, DW)