An incident in which an Israeli flag was removed from the roof of Sheffield Town Hall is being treated as a "hate crime", police have said.
The flag was taken down and replaced with a Palestinian one during a protest on 10 October.
South Yorkshire Police said it was investigating the incident as a racially-aggravated public order offence and "a hate crime".
The force added it had "carried out a range of different lines of inquiry".
It issued images of two men it wanted to trace as part of the investigation.
The decision to fly the Israeli flag was made after a request from central government three days after armed fighters from Hamas, which is proscribed as a terrorist group by the UK government, crossed from Gaza and killed 1,400 people.
Sheffield City Council Leader Tom Hunt, speaking at the the time, said the decision to fly the flag was made before Israel launched retaliatory airstrikes which have killed thousands of people.
The council pledged to review its policy on the flying of flags from the town hall.