Thanks to President Trump there may be choppy waters ahead for Greece's vital shipping industry.
As the US this week reinstated a global ban on Iranian oil exports, there are few countries outside of Iran that will be more affected by the move than Greece.
This is because Greece's merchant shipping fleet - the biggest in the world by tonnage - is also the largest transporter of Iranian oil.
Of the 217 oil tankers that ferried Iranian crude oil in the first six months of this year, 81, or 37%, were Greek-owned. The next highest was Iran's own National Iranian Tanker Company with 51 ships, followed by Denmark, China and Japan.
Although Greece is one of eight countries to be given a 180-day extension by the US - with the others being China, India, Italy, Japan, Turkey, South Korea and Taiwan - the White House has told those nations to start reducing their Iranian oil orders.
And with every other country told to stop immediately, or else face their own knock-on trade penalties from the US, Greece's oil tankers may be about to see a substantial drop in business.
'High risk'
Dimitrios Lyridis, associate professor of maritime transport at the National Technical University of Athens, says that most Greek shipping companies will comply with the ban, because the US is also targeting individual firms doing business with Iran.
As a result, continuing to ship Iranian oil could see Greek firms banned from doing business in the US and from using American ports.
"[Most] Greek shipping companies will comply with Trump's order," says Mr Lyridis.
"Many of these companies are on the US stock market, so the risk of non-compliance is just too high.
"I see them diversifying towards other markets, for instance, the Saudi one, currently under pressure to increase its oil output."
George Vaggelas, researcher and consultant on port economics, management and policy issues, at the University of the Aegean on the Greek island of Chios, agrees that Greek shipping firms listed in the US - such as Navios Maritime Holdings and Tsakos Energy Navigation - will comply.
'Laxer way'
However, Mr Vaggelas thinks that some Greek shipping firms without links to the US financial markets may continue to ship Iranian oil.
"These - though few - might continue serving Iranian oil exports at an increased risk," he says.
The shipping firms themselves are unwilling to comment given the seriousness of the situation, and none of those we contacted were prepared to give us a statement. The main Greek shipping trade unions also declined to provide a quote.
Mr Vaggelas is hopeful though that in practice the US will offer numerous countries - not just the eight given an extension - wiggle room.
He sees France and other European Union countries applying the oil embargo in a "laxer way" than the US, both to secure supplies, and because they want to keep the 2015 agreement on Iran's nuclear programme alive.
It was President Trump's decision to rip up this deal, negotiated by the administration of predecessor President Obama, that paved the way for the reinstatement of the embargo on Iranian oil exports.