The question suggests that many countries in some sense "intervened" [to stop] the Holocaust, but that a few didn't do so. In fact, no country "intervened" in order to stop the Holocaust. No country went to war against Nazi Germany because of the Holocaust. (Israel didn't exist as a clearly defined or independent country at the time). Politics doesn't work like that. In fact most countries that fought against Germany did so because they were attacked by Germany or one of its allies.
The United States intervened in the Vietnam War because we were afraid that the Vietnamese would become influenced with the tyranny of communism.
Intervene-stop by interfering in some way Invade-trespass with an opposing aggressive force.
Some people helped individuals during the Holocaust. Nobody tried to 'prevent the Holocaust' - even the Allies did not try to do that.
What were some conflicts for the holocaust children in the nazi war?"
The Holocaust and the United Nations Outreach Programme commemorated the Holocaust on November 15 in 2010 because the anniversary of the Kristallnacht was only a few days earlier on November 9 and 10, 1938. This was an anti-Jew riot that left around 100 Jews killed and thousands of their businesses vandalized.
Only some Holocaust Survivors are still alive.
I'm not sure what you mean by 'intervene'. If you mean, become a party to the case, you would have to have some reason to do so. For example, if two people were suing over ownership of a piece of property and you figure out it's really yours, then you might have grounds to intervene. The court would have to decide if you have standing to do so. Now, if by 'intervene' you mean submit a friend of the court brief, you have to ask the court for permission, and there may be restrictions, e.g. to ask the U.S Supreme Court for permission to submit a third-party brief you have to be an attorney licensed to practice and a member of the bar of the Supreme Court.
The Holocaust was abominable. It begins with the letter a.
The Holocaust is not some Jewish festival. Please see the related question.
The Holocaust was not a place to visit. The Holocaust was perpetrated by Christians against Jews. There were also, of course some Christian victims.
The increase in regional cooperation caused a recession and high inflation
The Holocaust ended in May 1945 (somewhat earlier in some places).