FourPacketsOfPeanuts has already given a good answer specifically about Israel's situation, but I want to say something about international law in general. Law may be written based on moral principles, but law is still not the same thing as morality. In our daily lives, we follow our moral principles because that's what we believe is right, and we follow the law because otherwise cops will put us in jail.

The situation for a sovereign country is different - there are no cops and there is no jail. If other countries wanted to take hostile action, they would even if there was no violation of international law, and if they did not want to take hostile action, the wouldn't even if there was a violation. Morality still exists (although morality at the scale of countries is necessarily not the same as morality at the scale of individuals) but the law might as well not exist because it is not enforced. It's just pretty language that may be quoted when a country does what it was going to do anyway.

I'm not trying to imply that I think that Israel is violating international law. I'm saying that discussing whether it is or not is a purely intellectual exercise with no practical relevance. If I support Israel but you convince me that it is technically breaking some law, I'm still not going to change my mind. If you oppose Israel but I convince you that it is technically obeying every law to the letter, you're still probably not going to change your mind.