South America has issues with colonial border since the europeans colonisers left, and later on also due to US intervensions. Nicaragua has additionally a horrifying past from the Sandinistas revolution -supported by people from all over the world- that succeeded and turned authoritarian, as they do. Not that long ago. Many people who fought in it are still alive. To my understanding they still suffer the consequences.
In order for the US-backed state of Israel to stop killing and starving civilians and children, all other countries need to demand it by diplomatic pressures, economic sanctions, boycott etc.