Well. They had to pull something out of the bag after failing to deliver on their side of the recent ceasefire agreement.
It is almost too obvious to mention that the real war crimes are the endless invasions and interventions, Iraq, Libya, Syria, that time after time kill tens of thousands of people directly and hundreds of thousands indirectly. Invasions and interventions which are never driven by legitimate reasons of self-defence but by a need to control markets, secure contracts, and in a wider sense spread their economic (and cultural) system world-wide.
But there is another crime here. By twisting the UN, international law and war crimes trials to suit their expedient purposes of the moment the US (and its vassal states like the UK) continually undermine any possibility of a real international frame-work developing. For example the sophist twisting of UN Resolution 1970 on Libya to legitmize a regime change operation which was never conceived of by the Security Council made Russia far less likely to work with the US on Syria. And it is almost too obvious to notice that the war crimes trials in the Hague seem to feature entirely people who’ve lost to the West. Slobodan Milošević of former Yugoslavia was on trial for the way in which he defended his country – but no sign of all those leaders of the West who authorised the illegal bombing of Yugoslavia in 1999 – to force Milošević to give up Kosovo. It doesn’t matter if all the civilians you kill are explained away as being ‘collateral damage’. If you shouldn’t be there in the first place what is that if not murder?
In Israel’s 2014 operation in Gaza approximately 2,100 – 2,300 Gazans were killed. 70-75% of these were civilians. Hundreds of children were killed. The figure is probably so high because the bombing was targeting ‘terrorist’ (according to the Israel) infrastructure located in a built-up area.  In the 2006 Lebanon-Israel war approximately 1,200 Lebanese civilians died. UNICEF estimated that 30% of Lebanese casualties were children under the age of 13.  Many deaths resulted from Israeli bombing in the built-up suburbs of South Beirut.
In both cases as far as this author can recall all we heard from the US and UK was the most mooted possible criticism of Israel’s bombing (which was carried out with US donated planes). In military terms the problem was that of ejecting/killing an entrenched ‘terrorist’ (if you like) enemy deeply dug into a built-up civilian area. And this is how it was justified at the time. In military terms the situation is analogous to that in Eastern Aleppo today – where the US denounces Russian and Syria action against Al-Qaeda and their allies as a war crime. This isn’t just ‘double-standards’. It is the utmost cynical disregard for human life; because if you turn on and off your concern for human rights as it suits your expedient interests it means in effect that you don’t care about human rights at all – ever. As President Putin commented at the UN in September 2015 in its interventions in the Middle East the US shows no consideration at all for human rights including the right to life. 
It is becoming increasingly evident that the underlying problem in world affairs is that the Western leaders (white in outlook, ‘middle-class’) think that their system; its values, economic system and culture (or lack of it) is the only valid one. A particular economic and political system which has arisen relatively recently and in contradistinction to which even today there are many different models on the planet. A set of social values (hedonism, immorality, secularism, materialism) which as the proposed value system for a mass culture is historically recent and historically relative. A level of corruption between politicians and private business so endemic that it doesn’t even appear as corruption. These are all taken as being absolutes – the only possibly valid models. They make the relative absolute. They believe their own reifications. In colloquial speech they are so up themselves that they can’t see the wood for the trees. And from all this it seems to follow that anyone who doesn’t share these values and this outlook can be bombed without conscience.