North Korea and Iran

The dictator in North Korea is threatening the US, that everyone knows.
What is less known is that this nut is also a threat to Israel.
How so?
Iran is following very closely the developments in the Korea peninsula and will want the blue prints or maybe a bomb or two itself.
What is to stop a Korean or Iranian submarine from taking a functional bomb from North Korea to Iran??
Can the transmission of such a weapon be stopped?
Is Israels or American Intelligence so advanced as to know or stop such a shipment?
It is likely that submarines are watched that go in and out of Iran, maybe.
But how do you stop a e-mail with instructions ??
President Trump is holding an emergency national security meeting in next few hours.
An Israeli official will likely deliver some intelligence.
Trump will need it.