Since Israel’s air salvo against the Gaza Strip escalated into a growing ground invasion, the death toll is soaring. Sunday was the deadliest day yet of the war, and Monday is on track to pass it considerably.

The death toll among Palestinians is up over 100 more today already, with the overall death toll now standing at 573, overwhelmingly civilians and including well over 100 children.

Another seven Israeli soldiers were killed today as well, bringing the overall toll on the Israeli side to 25 soldiers, and two civilians. Israeli officials continue to talk up further escalation of the conflict.

The question of when and how the war will actually end remains unclear, with no real exit strategy in place and Prime Minister Netanyahu making only vague references to a return of calm, even as he continues to make the situation less calm by adding more and more troops to the situation.

The war may also be expanding beyond the strip to some extent, with reports emerging of Israel’s military attacking an ammunition warehouse north of the Sudanese capital of Khartoum, apparently on the notion that the ammunition would eventually be funneled to Hamas.

The Islamic State group has threatened Christians in the Iraqi city of Mosul with death if they do not convert to Islam or pay a tax, Al Jazeera has learned.

The Sunni rebel group issued the orders in a letter after Friday prayers. The document, obtained by Al Jazeera, states that the order was issued after Christian leaders failed to attend a meeting called by the group.

In response, the group says in the letter that Christians must either convert to Islam, pay a tax on non-Muslims known as jiziya, or give up their posessions and leave the city. Failure to do so would result in a death penalty, "as a last resort".

Mosul, Iraq's second largest city, was overrun by the Islamic State group and allied rebel groups last month.

The Iraqi army units stationed in the city, most of whom were Shia, fled after the group crossed from Syria and attacked the north of Iraq.

Before the attack, Mosul's Christian community was estimated at 3,000. Many are believed to have already fled the city as part of an exodus of up to one-third of the population. Those who fled reported that churches and Christian-owned shops in the city were smashed.

The Islamic State's leader, Abu Bakr al-Baghdadi, held a sermon in Mosul's grand mosque two weeks ago, calling on all Muslims to unite behind his group.

The Islamic State, formerly known as ISIL, has issued similar demands in areas it control in Syria, and has posted pictures of Christians being crucified for disobeying orders in Raqqa.

Church leader‎s in Iraq have not responded to the threats officially.

Nickolay Mladenov, the head of the UN assistance mission In Iraq, condemned the order.

"Any persecution of minorities constitutes a crime against humanity and we urge all sides to protect civilians. We have produced a report listing attacks on civilians ‎and have brought this up at the highest levels of the Iraqi government."

BEIRUT — Militants from the Islamic State now control or threaten key facilities on the Euphrates and Tigris rivers, generating fears that the Al-Qaeda splinter group could turn off the taps to the Shiite south of Iraq, sparking a massive humanitarian crisis.

Last month's offensive across Iraq saw it overrun cities and battle for oil refineries as the national army melted away, but it has also been waging a war for water, trying to wrest control over rivers, dams and desalination plants in a bid to solidify its territorial gains.

Control of water is seen as key to the viability of the fledgling caliphate declared by Abu Bakr al-Baghdadi, leader of the group commonly known by many as ISIL. Without water, seasonal droughts cannot be managed, electricity cannot be generated, proper sanitation practices are near impossible and the local economy grinds to a virtual halt.

"When it comes to creating an Islamic state, it is not just about the control of geographic areas in Syria and Iraq. In order to form a viable state, one must control the state's most vital infrastructure, which in Iraq's case is water and oil," said Matthew Machowski, a Middle East security researcher in the British parliament and at Queen Mary University.

In Mosul, the first city ISIL captured, residents fled when the water and electricity were cut off but returned a few days later when the jihadist group was able to switch supplies back on, in a bid to engender support among the local population.

Iraq's 32 million people are entirely dependent on water flowing down from two great rivers in Turkey, the Euphrates and the Tigris. Where those waterways enter Iraq in the north, ISIL holds key dams and surrounding areas, leaving Shiite-majority southern Iraq vulnerable to the use of water as a strategic weapon.

In April, ISIL seized control of the Fallujah dam and its fighters released a wall of water from behind the barrage, destroying cropland 160 kilometers downstream and leaving millions of people without water in the predominately Shiite cities of Karbala, Najaf and Babil, while flooding areas as far away as Abu Ghraib.

"The intent behind the water release was to use water aggressively as a tool of destruction, targeting populations who live father south," said Russell Sticklor, co-author of Water Challenges and Cooperative Response in the Middle East and North Africa.

" ISIL is well aware of the strategic importance of controlling water access ... Control of this water infrastructure allows ISIL to control the faucet, and decide how much -- or how little -- water is released downstream. This is of great strategic importance because southern Iraq, the Shiite heartlands, needs water from the Tigris and the Euphrates to survive," he added. "They are in a very vulnerable position,"

U.N. Secretary-General Ban Ki-moon last week described the use of water as a weapon in Fallujah a "dangerous trend."