The plane landed on Wednesday at Elmas Airport in Cagliari, after taking off from Colorado.
There were around 10 people aboard, five of whom were in possession of American passports.
After a huge spike in coronavirus cases in Texas and other reopened states, Italy and other EU countries last week extended a travel restriction for US tourists for another two weeks.
The American passengers were repatriated, while the remaining five passengers, who were from Italy, New Zealand and England, could have stayed in Sardinia, following a mandatory quarantine for 14 days before being allowed to move freely.
However, at around 11:30 pm on Wednesday, they decided to return to the US with their friends, out of solidarity.
It’s unclear why the group thought they would be allowed to enter Italy.
The island’s government had “no responsibility for what happened”, regional president Christian Solinas said, adding that local authorities had attempted to find a solution that would have allowed the entire group to stay on Sardinia.
The national government’s “restrictive interpretation” of the rules had “inflicted grave damage to the international touristic credibility of our island and our sense of hospitality”, Solinas said.
Like other parts of southern Italy, Sardinia depends heavily on summer tourism and is seeking to draw visitors back while maintaining its low infection rate.
The region is one of four in Italy that requires travellers to register before they arrive, including Italian nationals and residents.
