Poland’s government on Friday marked the 10th anniversary of the plane crash that killed President Lech Kaczynski and 95 others by demanding that Russia return the wreckage of the plane.

The crash occurred as the Tu-154 air force jet carrying a high-level Polish delegation attempted to land in fog at an airport near Smolensk, Russia. It was Poland"s worst tragedy since World War II, killing not only the president and first lady, but many other top government and military officials.

The tragedy strained already difficult relations with neighbor Russia. It has also created a deep sense of grievance that has shaped Polish political life since then. Today the government is directed - mostly from behind the scenes - by the late president’s identical twin, Jaroslaw Kaczynski, who is chairman of the ruling conservative Law and Justice party. Kaczynski paid tribute to his twin and other victims at monuments to the victims in Warsaw, at the exact moment that the plane crashed on April 10, 2010.