a Dutch uncle a kindly but authoritative figure.

☞ Dutch here probably means no more than that the person described is not a genuine blood relation. In the mid 19th century I will talk to him like a Dutch uncle (meaning 'I will give him a lecture') was noted as being an American expression.

2006DigbyHullabaloo In the past when these situations would flare up, Israel would take an aggressive action to demonstrate that it wasn't a pushover and the US would step in like a Dutch uncle and reluctantly pull the pissed-off Israelis back.