It’s very likely Papadopoulos or the Trump Campaign was tipped off by Israeli intelligence
It’s more like a Greek connection. Pop worked on a deal between Israel and Greek Cyprus for a natural gas terminal. The US connection is that Noble Energy of Houston is in on the deal.
Looks like FBI/CIA tried to frame Pop for taking a bribe from Israelis, making him an ‘unregistered foreign agent’ of Israeli interests. It’s a transparent joke.