Merkel's political future hangs in the balance after having been the champion of refugees in Europe since the summer of 2015 when she declared her doors open to refugees — sparking the biggest mass movement of people in Europe since the Second World War.
She has championed the cause of a humanitarian response to the migrant crisis which has caused unrest within Germany and throughout Europe, with many claiming the sheer volume of migrants crossing the continent has disguised the rising threat of terrorism.
"It would be especially hard for us all to bear if it were confirmed that (the) person who committed this act was someone who sought protection and asylum," a shocked Merkel said in the aftermath of the Berlin attack.
Her interior minister Thomas de Maziere told reporters he had "no doubt" this was a terrorist attack.
Police originally detained a man who allegedly fled from the truck which was used to ram shoppers at the traditional Berlin Christmas mart. Local media reports suggest he is a 23-year-old migrant from Pakistan known to police for committing minor offenses and who had been registered as living in temporary accommodation at the now defunct Tempelhof airport.
However, German officials later said he was not the attacker, sparking fears that the attacker was still on the loose.
The impact of the attack in Germany's capital was summed up by the interior minister of the German state of Saarland, Klaus Bouillon, who told German broadcaster SR:
"We must say that we are in a state of war, although some people, who always only want to see good, do not want to see this."
Merkel has announced she will stand for a fourth term as German chancellor at the elections due in the Fall of 2017, but her credibility hangs on a thread as she attempts to balance her humanitarian stance on refugees and her principle role as chancellor — the security and wellbeing of her people.
The latest attack is the most devastating of a string of attacks to have hit Germany in the past year. In October, police arrested a 22-year-old Syrian refugee following the discovery of explosives and other bomb-making equipment at his apartment in Chemnitz, believed to be part of a plot to attack Berlin airport. The suspect hanged himself in a cell.
In July, 15 people were injured in a crowded wine bar near a music festival in the Bavarian town of Ansbach after a rejected Syrian asylum seeker detonated an explosive device, which also killed him.
Also in July, a 17-year-old asylum seeker wielding an axe and a knife seriously injured four tourists before being shot dead by police.