What's happening?

Throughout the day, bombs fell. Some were launched by HamasA militant Palestinian organisation, which has controlled the Gaza Strip since 2007. It is listed as a terrorist organisation in the UK., and landed in IsraelA country in the Middle East, and the only Jewish nation in the modern period. It is seen by Jews, Christians and Muslims as the Holy Land.. Others were launched from Israel, and landed in GazaThe smaller of two Palestinian territories, home to two million people. It is located on the Mediterranean coast, bordered by Israel and Egypt. .

On Sunday, Israel declared war on Hamas. It came after an attack by Hamas killed hundreds of Israelis. The soldiers that will be fighting this war for Israel come from the Israel Defence Forces. It is known as one of the world's strongest armies.

The IDF was created in 1948. All Israelis, apart from Arabs, have to join the army for two to three years from the age of 18. The IDF is the only army in the world which also forces women to join. After the Hamas attacks, the army has called up 300,000 people who are ready to serve at any time.

The attack by Hamas on Saturday morning took the IDF by surprise. But expertsSomeone who knows a lot about a particular subject. say that the IDF has a long history of getting stronger after a failure - so Hamas should watch out.

Writer Eliot Cohen points out that because Israel is a small country, its soldiers are "fighting to protect their homes and family". This makes the army stronger, he says.

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But he also thinks the IDF has a weakness: overconfidence. Hamas's fighters will be just as eager to win this war as the IDF - and they have learnt from watching the IDF too.

Is all killing wrong?

Yes! Nobody has the right to take someone else's life. When one side drops bombs to get back at the other, it will only ever make the situation worse.

No! Sometimes we have to do all we can to protect ourselves, and sadly that can mean killing people.