This year one of the holiest days in Islam falls within hours of the 15th anniversary of the September 11th attacks.

Muslims will mark Eid al-Adaha on September 12th, but some begin festivities the night before.

Some celebrants and the Detroit office of the FBI expressed concerns that non-Muslims may misinterpret the annual holiday as a celebration of the attacks.

"I have some friends who have said things like, you know, I don't know if I'm going to wear my hijab or I don't know if I'm going to wear it the way that I typically wear it or I don't know if I'm going to go to an Eid party or really be visibly celebrating on line," said Asha Noor, a local Muslim activist.

The FBI said it is working with local police departments to keep mosques safe during the holiday. It has not received any credible threats.

The proximity of Eid, which is determined by a lunar calendar, and the remembrance of 9/11 comes amid a heightened concern about Islamaphobia in the wake of attacks by ISIS abroad and the rise of Republican presidential candidate Donald Trump at home.

On the campaign trail Trump has advocated against Muslim immigration and supports the surveillance of mosques in the United States.

Trump claimed that he saw Muslim-Americans celebrating the attacks in New Jersey 15 years ago.