ROME — The scheduled entry into service of a satellite-based global communications system, which has cost the US military $7.6 billion, is in danger of slipping thanks to legal battles in Sicily.

The Mobile User Objective System (MUOS) network, based on a series of satellites and four ground stations, spanning the globe, is set to provide voice and data communications to US military personnel and platforms around the world, even when they are under thick forest canopies. While a portion of the system is operating, the Sicilian station would provide about one-fourth of the global coverage.

Run by the US Navy, MUOS will operate like a smartphone network in space, officials claim, using a high-speed Internet Protocol-based system functioning based on a commercial cellular standard waveform modified for military use.

Of five satellites planned for the constellation, three have been launched — the third from Cape Canaveral in January — a fourth is due to be launched this summer and the fifth and final satellite is set to go into orbit in 2016.

Testing should occur in December and full operational capability is due in 2017, said Steve Davis, a spokesman for the Navy's Space and Naval Warfare Systems Command.

Communications will bounce up and down between the satellites and four ground stations, in Australia, Hawaii, Virginia and Sicily, which each equipped with boast three large dishes pointing at the sky. The stations in Australia, Hawaii and Virginia all completed testing by 2013.

But that leaves the site at Niscemi, Sicily, which is yet untested, thanks to legal challenges and local protest that means the station is currently under sequester by a local judge, putting all the deadlines in doubt.

Objections from locals are based on reports that electromagnetic emissions produced by the giant dishes are dangerous to their health, while the site has also allegedly violated a protected stretch of countryside.

Despite backing from the government in Rome, locals clashed violently with police in 2013 during construction of the site, and the governor of Sicily, which enjoys substantial autonomy, that year opted to call a halt to the program that year pending further emission tests.

This year, the site was sequestered by a local judge on April 1. , before An appeal against by sequester lodged by the Italian Ministry of Defense was turned down April 27. Another court hearing is due July 8.

Judges have argued that permits issued to allow the original construction of the site were handed out in violation of Italian law.

Protesters on the island have become even less well disposed to the US military since the accidental death of Sicily native Giovanni Lo Porto, who was a hostage in Pakistan, in a January US drone strike.

Despite months of protests and sequesters, Lockheed Martin, the prime contractor on the program, has completed construction of the $63 million site, leaving it to the US Navy to hope it can start testing soon.

"The facility was built with all the legal permits, and we have worked with the Italian government to test all electromagnetic emissions and they are well below standards set by Italy, the EU and the US," said Jeffrey Galvin, a spokesman for the US Embassy in Rome.

"The site has been shut down twice before, and we hope the appeal lodged by the Italian government will go through," he said. "Our aim is to resume testing at the end of this year or the start of 2016. By the time of the launch of the last satellite our aim is to have the site fully operational."

With the last satellite due to be launched in 2016, and given the snail's pace of Italian justice, it will be a tight race to get Niscemi up and running, assuming it is eventually cleared by the courts.

One Italian analyst said he believed the courts would come around.

"I think the matter will eventually be taken up by a state court in Rome and will be unblocked, on condition that a rigorous system for checking emissions is set up," said Francesco Tosato, an analyst at the CESI think tank in Rome.

If Niscemi is delayed, or even shut down, Galvin said MUOS would only reach 75 percent of its potential coverage.

"MUOS is up and running in the regions covered by the existing satellites and ground stations," he said. "The ground station at Niscemi will cover approximately one quarter of the globe, including Africa from the Indian Ocean in the east to the Atlantic Ocean in the west once it becomes operational."

The row in Sicily comes as the island returns to being a strategic Italian outpost after it was used as a base for fighters bombing the regime of Col. Moammar Gadhafi in 2011.

Four years on, as migrants and refugees pour out of Libya, the Italian Navy is picking up thousands in the Mediterranean as they set sail on rickety boats to reach Italy. On May 7, a British amphibious ship, the HMS Bulwark, joined the effort, picking up over 100 migrants as their inflatable dinghy began to deflate at sea after they left Libya.