The increased attacks from Gaza this week are a disturbing reminder that calm is fragile in this region. On Tuesday, mortar shells hit Israeli communities, damaging a kindergarten, among other places, fortunately just before the children arrived. And on Monday, several homes in Sderot were hit by machine-gun fire from Gaza.No one was surprised by this escalation. Hamas has been searching for ways to get the Gaza Strip back on the world’s agenda. It tried the “Great March of Return” but with limited success. Instigating a war with Israel has the potential to do the job.There are reports that the latest attacks were carried out by Islamic Jihad, a terrorist organization working with Iranian backing whose name says it all. But clearly Hamas can decide whether to fan the flames or rein in the terrorism.There is a tendency to look on mortar and machine gun fire as less serious dangers. That would be a mistake. Gazan mortars have in the past killed residents in southern kibbutzim. Unlike rocket fire, for which there are usually some seconds of warning, mortars hit without a Red Alert siren sounding first. Mortar shells are considered “primitive,” especially compared to long-range rockets, but we need to ask ourselves: Is a life in Ashkelon or Tel Aviv more valuable than the life of a resident of Sderot or Kibbutz Nir Am? Should a mortar kill, the response would have to be more serious and the situation could quickly escalate. This is particularly problematic with an enemy such as Hamas and Islamic Jihad that uses its own population as human shields. These terrorist organizations, based on the cult of martyrdom, want blood, whether it is Palestinian or Israeli. They are overjoyed if Israelis are killed, but an Israeli response in which Gazans are killed – innocents or members of their organizations – is considered a victory, the chance to put the Palestinians back in the spotlight and plea for more international funding while turning Israel into the bad guy.The current tension could go either way: further escalation or another uneasy and informal cease-fire.Hamas is not openly claiming credit for these attacks, but nevertheless, since it seized control of the Gaza Strip in 2007, Hamas has to be considered responsible. Several international players pull the strings in Gaza, including Iran, Turkey and Qatar. Similarly, any effort to calm the situation must include Egypt, which shares a border with Gaza, and the Palestinian Authority. The Fatah-controlled PA is the sworn enemy of Hamas and responsible to a great extent for the terrible conditions that the ordinary Gazan faces.There is mounting pressure on Israel to make concessions to Hamas to ease the situation in the Strip. Although Israel undoubtedly has a role to play, it should not be the primary one. Israel withdrew entirely from Gaza in 2005, uprooting some 8,000 Jewish residents. There are just two Israeli soldiers in Gaza, Hadar Goldin and Oron Shaul: Both were killed in 2014 during Operation Protective Edge and their bodies abducted via attack tunnels. In addition there are two Israeli civilians being held there against their will. No solution to Gaza will be complete without their return and closure for the Goldin and Shaul families.This week Public Security Minister Gilad Erdan called on the Prisons Service to prevent Hamas security prisoners from being able to watch the World Cup next month, as a means of putting pressure on Hamas to release the missing Israelis. This was quickly labeled as unnecessarily cruel collective punishment. But more serious measures need to be taken.Israel cannot be afford to give up its deterrence. The world dismisses the incendiary kites dispatched from Gaza over the past two months. This week an explosive- laden drone was launched on the South from Gaza and by Tuesday residents were dealing with rockets and mortar fire. This cannot be allowed to continue.Israel does not want a war, but without deterrence this is inevitable. Undoubtedly there will be calls for Israeli restraint. But the question shouldn’t be what is the appropriate or “proportionate” Israeli response, but why the world thinks it acceptable that even one mortar shell or rocket should be fired at a kindergarten. Even after Israel’s response, the world should stand as one against Hamas’s aggression.