Good evening I'm John yang.

President trump's pressure on Venezuelan leader Nicolas maduro mounted today as the coast gua went after another oil tank that are U.S.

Officials say was helping Venezuela get around sanctions.

If they intercept it, it would be the third time in less than - - in two weeks and the second time this weekend.

The coast guard boarded a Panamanian tanker carrying Venezuela crude oil to Asia.

Venezuela called it theft and hijacking.

Last week, president trump announced a total and complete blockade of all sanctioned tankers headed to and from Venezuela.

Idrees Ali is the national security correspond for reuters.

Idrees, what's the latest and what do we know about today's pursuit?

Idrees: Yeah, this has been a pretty busy weekend when it comes to coast guard activity around Venezuela.

And so what we know qulib is that earlier today on Sunday, the U.S.

Coast guard with help from the U.S.

Navy tried to interdict a vessel that was sanctioned by the United States and has historically carried oil to and from Venezuela.

The latest reporting we have is that its pursuit is still ongoing because vessel in question has not given up, has not allowed them to come onboard and so a pretty active situation.

We don't know how it's going to get resolved.

But it is in international waters and it is sanctioned.

And so it's pretty much in line with what president trump said the U.S.

Would be doing which is going after sanctioned oil tankers that are carrying oil to and from Venezuela.

John: Is this -- this all started with drug boats in the caribbean and eastern pacific but how much of an escalation does this represent?

Idrees: You know, from the officials I've talked to, and the experts we've talked to, this does represent an escalation because it's one thing to be striking suspected drug boats that are in and around Venezuela and another thing to put pressure on the economic lifeline of Venezuelan president maduro and that's oil.

It's really one of the few things that brings in money for the government.

And when you go after that you are really sending a message that this isn't just about drug boats, drugs, it's about cutting off really, you know, the scarce resources maduro relies on and send a message to the Venezuelan government and people that the United States is really focused not just on going after drugs but potentially getting rid of maduro.

And I think we're seeing that in action.

John: What's the legal basis or international law basis for what the administration is doing?

Idrees: So much like most legal things, there is a debate, and not everyone agrees on what the legal basis is.

So by definition, the coast guard has different authorities.

And so they do have the authority to go after state vessels or vessels that they are, you know, suspect are carrying goods like narcotics and really check the registries.

The coast guard has quite a bit of leeway.

That's what the administration is saying.

Look, these are vessels that the U.S.

Has sanctioned.

They could be carrying dangerous goods.

And they're carrying sanctioned oil in many cases or that's the allegation.

Legal experts disagree.

They say just because the vessel is sanctioned by a country does not mean that you can board it.

So there's a legal sort of jostle going on right now.

And it really comes against the backdrop of what the precedent might be, right?

So if you have the Chinese sanctioning a vessel, U.S.

Or allied and they say we're going to go -- board this very much because it's sanctioned I think legal experts are saying look, you can't have that and the rules are -- international order doesn't allow that.

So there's a real debate about what the legal basis is.

And again, the whole campaign we've seen since September has been legally questionable.

The strikes against suspected drug vessels has really been under a microscope when it comes to legalese.

Can you really strike a boat that's carrying any drugs?

Can you really kill someone for that?

And most of the legal experts say no.

John: Are all three ships involved in this, are they all on the sanctioned list?

U.S.

Sanction list?

Idrees: So the first one was on the sanction list.

The one today is also on the sanctioned list.

The one on Saturday was interesting because actually it was not on the sanctioned list.

It was -- what's known as a shadow vessel.

So it's not sanctioned.

But it's a vessel that is essentially spoofing its locations, changing its name, changing its location to get around some of the restrictions but it was not sanctioned and I think that's what raised a lot of eyebrows for people.

The administration said -- might not be sanctioned but carrying sanctioned oil.

That isn't what president trump said would be happening.

He said the U.S.

Would be going after sanctioned tankers and two out of the three met the criteria.

The one yesterday on Saturday did not.

And I think that's using a lot of -- raising a lot of concerns because some of that oil was destined for China so the Chinese government will have a lot to say about that.

John: In about the 45 seconds left we have left president trump talks about taking this onshore in Venezuela.

Remind us what the military buildup has been like in the region.

Idrees: Yeah.

The military buildup has been huge.

In the past week, we have seen the administration, you know, really lay out its strategy and its national security strategy document saying they want to return to the Monroe doctrine which is basically saying the U.S.

Is going to look after the western hemisphere.

Every other country should stay out and to that end they have deployed an aircraft carrier about 20f-35 jets and at least 11 other warships.

And so the buildup is just massive.

It's not something you see just for strikes against suspected vessels or going after sanctioned oil tankers.

It really is if you are looking to change not just a regime but really the way the western hemisphere currently is and how the U.S.

Is interacting with it.

John: Idrees Ali of reuters.