At a summit in Brussels on Thursday, EU leaders backed plans to spend more on defense amid fears that Russia, emboldened by its war in Ukraine, may attack an EU country next and that Europe can no longer rely on the U.S. to come to its aid.
Merz's tougher stance on security and migration reflects a changing political landscape, where the far-right Alternative for Germany (AfD) has surged to become the country's second-largest party.
Germany's plans to tighten migration laws did not clash with pan-European migration rules to be introduced by Brussels, Merz said.
"We want European solidarity...but Germany also naturally has a right to defend its own security and order," he said.
Merz has said he wants to form a coalition by Easter, which falls on April 20 this year.