Leader of governing party Law and Justice (PiS) Jaroslaw Kaczynski (Front) pays his respects at the graves of Smolensk victims in Warsaw, Poland, on April 10, 2019. Poland's political leaders are leading throughout Wednesday a series of commemorative events to mark the ninth anniversary of the Smolensk plane crash, which killed 96 people, including former Polish President Lech Kaczynski. (Xinhua/Jaap Arriens)