chrisgaff1000, "Once he is in international waters he is not subject to the home laws until he arrives back"

No, that is wrong. Google Article 94, Duties of the flag State.

Poirot is also wrong. However I have already covered the duties of the owners and masters of vessels in another thread that doubtless Poirot read at the time. In essence, the responsibilities of the woners and master are onerous (reasonable considering the powers of a ship's master!).

In this case there is reasonable suspicion of illegal activity from the behaviour of the masters and owners, incuding behaviour that could put the ship's company, the passengers and the vessel at risk. Not only is it reasonable for a warship to intervene, it would not be complying with the international rules and expectations not to do so.

It is hypocritical that some here would support the extreme acts of Sea Shepherd that put lives and ships at risk to save whales, but they object to navy intervention at sea to preserve life, ships and laws, national and international. The lunar Left and Greens never have to be responsible for the unforseen consequences of their actions: throw open the doors, support criminal gangs and drown people. That is the Left for you, barking mad and proud of it.

P,

In international law, any country has the right to intercept any vessel headed for its shores. This has been done routinely by the US the UK etc.

It a boat from Indonesia was heading to PNG, this would then be illegal.