Wired has a story about a possible GPS spoofing attack by Russia:
After trawling through AIS data from recent years, evidence of spoofing becomes clear. Goward says GPS data has placed ships at three different airports and there have been other interesting anomalies. "We would find very large oil tankers who could travel at the maximum speed at 15 knots," says Goward, who was formerly director for Marine Transportation Systems at the US Coast Guard. "Their AIS, which is powered by GPS, would be saying they had sped up to 60 to 65 knots for an hour and then suddenly stopped. They had done that several times."
All of the evidence from the Black Sea points towards a co-ordinated attempt to disrupt GPS. A recently published report from NRK found that 24 vessels appeared at Gelendzhik airport around the same time as the Atria. When contacted, a US Coast Guard representative refused to comment on the incident, saying any GPS disruption that warranted further investigation would be passed onto the Department of Defence.
"It looks like a sophisticated attack, by somebody who knew what they were doing and were just testing the system," Bonenberg says. Humphreys told NRK it "strongly" looks like a spoofing incident. Fire Eye's Brubaker, agreed, saying the activity looked intentional. Goward is also confident that GPS were purposely disrupted. "What this case shows us is there are entities out there that are willing and eager to disrupt satellite navigation systems for whatever reason and they can do it over a fairly large area and in a sophisticated way," he says. "They're not just broadcasting a stronger signal and denying service this is worse they're providing hazardously misleading information."
from GPS Spoofing Attacks