"...usual disregard for International Law..."
Israel does a decent job of complying with International Law insofar as may be practicable.
Where it is not practicable, we are dealing in matters of safety-security and survival, and, still, they generally violate to as minimal an extent as may be practicable, while ensuring safety-security and survival.
Survival and safety-security - both short- and long-term - always trump International Law in the minds of the so-called violating party.
Always.
Sometimes, it's a valid perception; sometimes not.
In the case of Israel, it's usually a valid perception, and they have the balls to do what is needed, to ensure their safety-security and survival, despite what anyone else thinks.
As would any head of a family - taking care of his own first, with as little damage to others as may be practicable, but regardless of what others think - his family coming first in his calculations and actions. Human. Understandable. Laudable.
There is not a sane country on the face of the planet that would trade its survival for strict adherence to International Law.
The Israelis are no different in that regard.
They are a nation of refugees from a horrific slaughter 70 years ago, with that slaughter still within living memory, and they aren't about to take your shit - or mine - or that of some of the weasels at the UN General Assembly - to block their 2000 year-old goal of reclaiming Eretz Yisrael as a final redoubt and homeland for Jews around the world, now that the world has demonstrated a penchant for slaughtering them in their millions.
Eretz Yisrael is the price the world must pay for the Holocaust. The Muslim-Arab Palestinians of the region are merely in-the-way, and need to be moved elsewhere.
The Jews of Israel are a people under siege and they fully intend to survive this time, and ultimately to thrive; not willing to take shit from either you or I, on the road to reclaiming the full extent of their old ancestral and spiritual homeland.
Their former monstrous and cosmic suffering as a people, and the courage that they have demonstrated in holding themselves together for 2000 years and reclaiming what was once theirs, has excited the admiration and support of much of the world, even amongst those who publicly cluck their tongues and wag their fingers at Israel, in order to keep the Arab oil flowing their way.
Not to mention the 'Guilt Factor' over the Holocaust, and the extra slack that the Israelis get from The West as a sort of unspoken (but very real) penance for allowing so many of them to be killed in the 1930s and 1940s.
So, insofar as International Law is concerned, if the Israelis aren't actually slaughtering the Palestinians - sweeping through Gaza and the West Bank and killing everything that moves - then The World is willing to give them a lot more latitude than most others get, due to their special circumstances and needs.
The UN is a toothless old ladies' debating society.
It is a place where the Lilliputians of the world band together to try to keep the Gullivers in check.
Set up by the Gullivers to keep the Lilliputians quiet.
And controlled - ultimately - through the Five Permanent Gullivers on the Security Council.
In the long run, International Law is what the Five Gullivers say it is, or what they'll tolerate.
If you're a mid-sized type - a Regional Gulliver - bigger or stronger than your neighbors but not big enough to have a seat amongst the Big Five Gullivers - and if you're good friends with one of the Big Five Gullivers - you can pretty much do what you want, within reason, so long as you don't go around massacring whole populations and whatnot.
Annex their old lands when they abandon them or as spoils of war? No problem.
Seize and annex additional parcels of land when they won't reach a compromise and continue to shoot at you? No problem.
Wall-off the Lilliputians so they can't hurt your own people with guns and suicide vests? No problem.
Smack the shit out of the Lilliputians when they fire rockets at your people or dig tunnels for guerrilla sorties? No problem.
Evict and expel them to other Lilliputian lands when you've had enough? No problem.
It's called 'Friends with Benefits' - being Best Buds with one of the Big Five Gullivers.
Of course, it helps to have a track record as a much-savaged Lilliputian clan yourselves.
The UN General Assembly - the global town hall for the Lilliputians - will ***** and piss and moan and 'resolve' - dominated as it is by Arab sympathizers and Lilliputians who need Arab oil much worse than we do, or who do not face such in-your-face hostile populations themselves, or wussies who couldn't fight their way out of a wet paper bag.
The UN Security Council - dominated by the Big Five Gullivers - ultimately decides whether to take seriously the proceedings and 'resolve' of the Lilliputians in the General Assembly.
The UN?
Don't make me laugh.
Some of its agencies do good and necessary work around the world - bless 'em.
As a world-governance body, however... you attribute far too much effectiveness to them and far too little skepticism and powerlessness.
In the Real World, it doesn't work that way.
"...Israel should leave the UN or be expelled!"
Israel can certainly leave the UN if it likes, but I think that would be a mistake; always better to have a seat in the Global Town Hall than not.
As to being 'expelled', well... to expel Israel, you would have to expel a sizable number of other members using the same grounds or basis - Lilliputians and Gullivers alike.
Besides, Israel has a very good friend amongst the Big Five Gullivers, and you need the 'recommendation' and 'approval' of the Security Council, before the Lilliputians in the General Assembly are allowed to vote on expelling, under the UN Charter, Section II, Articles 5 and 6.
See how that works? Isn't that cool?