The Israeli military says it has struck a pair of Hamas militant sites in Gaza after a projectile fired from the seaside territory landed in southern Israel, The Associated Press reports.

Tuesday, June 27’s early morning strikes hit training sites but caused no injuries. The projectile on Israel fell in an open area and no one was hurt.

The attack and retaliation broke a period of relative calm along the hostile border.

Israel holds Gaza’s Hamas rulers responsible for all fire out of the strip — even rockets launched by any of the various militant groups challenging Hamas.

Israel and Hamas have fought three wars since the Islamic militant group took control of Gaza a decade ago, most recently in 2014. A cease-fire has largely held since then.