Germany's government has named Boris Pistorius as the new defence minister as pressure mounts on Berlin from Western allies to allow Ukraine to use German-made tanks in the war with Russia.
Christine Lambrecht resigned as defence minister on Monday, ahead of a conference on Friday at the US military base in Ramstein on Western plans to provide Kyiv with more arms.
Until now, Germany has been cautious about approving the despatch of heavy Leopard tanks due to worries that such a move could be seen as an escalation of the war.
Other countries with such tanks also need Berlin's approval before they can be passed on to another country.
"There are important decisions to be made in the short term, in particular the urgent question of how we continue to support Ukraine in its right to self-defence," Economy Minister Robert Habeck, said in a statement.
"Germany bears a responsibility here and has major tasks to accomplish."
Pistorius, 62, who has carried out his military service, has been interior minister in Lower Saxony since 2013.
He ran for the leadership of the Social Democrat (SPD) party in 2019 and is known for taking a hard line on security issues.
He gained a national profile during the 2015 migrant crisis when he espoused a restrictive migrant policy.
"Pistorius is an extremely experienced politician who is tried and tested in administration, has dealt with security policy for years," Chancellor Olaf Scholz said.
"With his competence, assertiveness and big heart, he is exactly the right person to lead the Bundeswehr (armed forces) through this turning point."
Pistorius has been in a relationship with Doris Schroeder-Kopf, the ex-wife of former chancellor Gerhard Schroeder.
Schroeder has drawn sharp criticism from inside Germany and abroad for his close ties to Russian President Vladimir Putin.
Pistorius was also a member of the Bundesrat upper house of parliament German-Russian friendship group before it was dissolved in April.
A further priority will be to sort out German defence capabilities, under the spotlight since several Puma infantry tanks were put out of service in a recent drill.
At his disposal is a 100 billion-euro ($A156 billion) special fund for defence, agreed after Russia invaded Ukraine nearly a year ago.