Although Fourth of July security advisories are fairly common, this year's bulletin sent to local law enforcement in May carries weight because ISIS has asked its supporters to carry out attacks around the world, NBC News reported. Authorities have said they are unaware of any specific or credible threat inside the country. But there is mounting evidence that many of those ISIS supporters, including so-called lone wolves who have been inspired if not explicitly backed by the group, are heeding those calls. In the New York region alone, authorities have arrested five people on terror-related charges in the past month. "This year is different from other years because of the real links that come across between ISIS' fighters on the ground connecting with radicalized individuals or self-radicalized individuals online in the homeland," said Laith Alkhouri, a co-founder of security consulting firm Flashpoint Intelligence, an NBC News partner.