Palestinian protesters clash with Israeli troops in central Gaza Strip, Dec. 13, 2019. (Photo by Khaled Omar/Xinhua)

A Palestinian protester uses a slingshot to throw back a tear gas canister fired by Israeli troops during clashes in east Gaza City, Dec. 13, 2019. (Photo by Mohammed Dahman/Xinhua)

A Palestinian protester uses a slingshot to throw back a tear gas canister fired by Israeli troops during clashes in central Gaza Strip, Dec. 13, 2019. (Photo by Khaled Omar/Xinhua)