Legal Question in Wills and Trusts in California

It depends on the tax treaty between the US and Monaco, if any.

You are not going to find an answer to this on the internet. You need to contact the tax department of a large international law firm.

The reason that this might be taxed differently than if everyone lived in the USA is in that situation the money earned by the parents has already been taxed once so the government is willing to waive gifts of no more than $15,000 a year by one person to another, but in the case you cite no USA taxes have yet been paid and allowing it would permit the avoidance of paying US taxes. So you have to speak to someone who handles such matters to see what can be done.