US Secretary of State John Kerry has called the terror attacks in Paris "France's 9/11".
Seventeen people were killed in three days of bloodshed in the French capital last week, including police officers and staff at satirical magazine Charlie Hebdo.
Mr Kerry made the comments as he visited the kosher supermarket in Paris where four hostages were killed in an armed siege one week ago today.
He laid a wreath outside the deli in tribute to those shot dead by gunman Amedy Coulibaly, one of three men responsible for the string of attacks.
Speaking to French president Francois Hollande, Mr Kerry said:
I think you know that you have the full and heartfelt condolences of the American people and I know you know that we share the pain and the horror of everything that you went through.
Together we need to find the right responses and this is the purpose of our meeting here today, beyond the friendship.
About 7,000 French Jewish people left the country last year and have moved to Israel because they did not feel safe.
The aunt of a man killed while trying to overpower gunman Amedy Coulibaly has told ITV News her family is fearful of their future in France.
A Muslim cleric in Pakistan has held a ceremony to honour Cherif and Said Kouachi, the two men suspected of the Charlie Hebdo massacre.