Stop mourning for Israel's enemies

One of the most disturbing aspects of the recent opening of the US Embassy in Jerusalem was the grief and sorrow expressed by many liberal Jews over the death of 62 Arabs the same day in violent riots led by Hamas. The Arabs were killed by Israeli soldiers while trying to break through the Gaza border fence in order to kill Jews on the other side, and Hamas made no secret of its murderous intentions. Yet many persisted in falsely accusing Israel of "massacring" unarmed civilians. Senator Bernie Sanders said that Israel should be condemned for the deaths in Gaza, while Senator Dianne Feinstein expressed deep disappointment that the United States blocked a UN investigation into Israel's actions. 
But the facts about Gaza are clear. These were not peaceful demonstrations. They were calculated acts of aggression organized and led by Hamas, whose charter explicitly calls for the death of all Jews everywhere, and which regards being "martyred" in battle against Jews as the highest possible achievement.
Hamas operatives wearing civilian clothes with hidden weapons under their clothing surrounded themselves with numerous "human shields," including women and children, and charged the border fence, hoping that Israel's hesitation to shoot civilians would enable some Hamas men to get past the barricades, in which case they would head straight to nearby Jewish communities, to which they had been given maps, in order to slaughter the inhabitants. These are the people whose deaths Sanders and Feinstein are grieving about.
It's a testament to Israel's discipline and self-restraint that the death toll was as low as it was, and that the vast majority of those killed were not civilians, but Hamas operatives, as confirmed by Hamas itself. Hamas, rather than mourning them, celebrated them as "holy martyrs" and promised many more such martyrs in the future.
But the question is, why would Jewish people have so much sympathy for Israel's enemies, and so little sympathy for Jews who are the targets of their attacks? Some say it's a case of self-loathing Jews who can never find anything good to say about Israel, or anything bad to say about its adversaries. But I suspect the real reason may be different. I suspect it might result from a deep misunderstanding of what Judaism actually stands for.
Many liberal Jews seem to think it's a core Jewish value to always side with the underdog in any conflict, regardless of the merits of the case. The reasoning is that since we've been victims ourselves, we must always empathize with victims, no matter how they got that way. But this is not what Judaism teaches. Judaism teaches that in matters of judgment we must not show preference for either the rich or the poor, or the strong or the weak, but must judge every case on it own merits. 
In the early days of the Jewish state, Israel was seen as weak compared to its enemies, so it got a lot of sympathy and support. But now that's it's grown stronger, its enemies are the ones who get the sympathy, as if being the weaker party in a conflict automatically confers moral virtue, while being the stronger implies moral depravity. 
The habit of always siding with the perceived underdog not only strengthens and encourages groups like Hamas, it harms world Jewry in other ways as well. Among liberal Jews today, one of the noblest things you can do is "social action," which usually means interjecting yourself into conflicts in which you're not a direct party, in order to help the weaker side against the stronger. In fact, what this often does is prolong and exacerbate conflicts, as well as generate new conflicts. It also gives credence to the anti-Jewish accusation that Jews are always fomenting wars and divisions, and it greatly escalates anger and hostility to Jews worldwide.
Israel has many adversaries, but few cause more damage than Jews who claim they're acting according to Jewish values when they're doing nothing of the kind, who denounce Israel in every international forum for defending itself against its enemies, who grieve and mourn for those who are killed while trying to murder Jews, and who resist every attempt by Israel to assert its national sovereignty or its historic heritage, all in the name of standing up for an alleged "underdog."