The Israel Air Force struck three Hamas terror infrastructure sites in the Gaza Strip in response to an earlier rocket fired at Israel, the IDF Spokesperson's Unit said Thursday morning. The northern Gaza sites reportedly belonged to the Hamas terror group.The IDF said that they hold Hamas responsible for anything that happens in the Gaza Strip and will "do its utmost to preserve the calm in Israel's southern cities."Late on Wednesday night, a mortar shell landed in Israel in an open field in the Eshkol Regional Council, near the security fence with Gaza.The mortar firing did not prompt a red alert siren and there were no reports of damage or injury from the incident. This latest rocket comes one day after firings along the country's northern border. On Tuesday, three mortar shells fired from Syria slammed into the Golan Heights, ramping up tensions on the northern border hours after IAF jets struck Syrian artillery guns and were targeted by two surface-to-air missiles fired at them from Syria in the predawn hours of Tuesday.The Israeli jets had struck in southern Syria in response to earlier cross-border stray fire into Israel, in line with a policy of retaliating to each case, whether stray or deliberate. Yaakov Lappin contributed to this report.