Germany has admitted that mistakes were made in the aftermath of last year's attack on a Christmas market in Berlin that left 12 dead.
"Everything humanly possible" was being done to help those affected and improve security, Chancellor Angela Merkel said on the first anniversary of the attack.
Mrs Merkel has come under fire for her government's response.
Families have said they were not given timely information and that they were sent bills for the costs of autopsies.
After a private ceremony for the bereaved and emergency workers, Mrs Merkel said it was time to work to "correct the things that went wrong".
"Not only to guarantee security, but to give those whose lives were destroyed or impacted, the chance to return to their lives as well as possible," she added.
The chancellor also attended an event that unveiled a memorial for the victims at Berlin's Breitscheidplatz, the site of the Christmas market.
Several family members had accused Mrs Merkel of "inaction", saying that she had failed to reach out to them. She met victims' relatives for the first time on Monday, and described the conversation as "brutally honest".
Earlier, in an article in the Tagesspiegel newspaper (in German), Justice Minister Heiko Maas acknowledged the country was not "sufficiently prepared" for the consequences of such an attack, saying: "For this we can only apologise to the victims and surviving relatives".
He proposed the creation of a government co-ordination office to improve communication with victims of future attacks and called for a change in the law so that all victims could be treated and compensated equally, regardless of their nationalities or the circumstances of the attack.
A report commissioned by the government and released last week cited a number of failures in the response to the attack, including delays in confirming the identities of the victims to their relatives.
A separate report in October revealed "gross mistakes" by German police and security services.
Anis Amri, a Tunisian asylum seeker who drove a lorry into the crowded market, was shot and killed in Italy four days after the attack.