Iran’s President Hassan Rouhani and Foreign Minister Mohammad Javad Zarif homed in on Switzerland and Austria, two small but independent-minded countries, to avoid having the accord being flattened under the weight of US sanctions.

Rouhani has stated on numerous occasions it is time to move beyond warm words of support from European states and produce concrete action when it comes to economic relations. Tehran should not bank on any miracles.

The final communique kept the deal alive — which is no small accomplishment with transatlantic relations at a new low — but was vague on how to support global European companies with a dependency on US investment to stay in Iran.

A Middle East-based European diplomat told me that the aggressive stance by the Trump administration is forcing the European Union to find an agreement that maintains some leverage on Iran while remaining engaged. If not, this diplomat with both Russian and EU experience contends, the Iranian file would be happily taken over by Russia, China and Turkey.

Ahead of the Vienna talks, the US State Department gave a briefing to reinforce the position of the Trump administration that it will use the heft of the US capital markets to lean on European companies who chose to challenge secondary sanctions imposed by the US.

“We will not hesitate of take action when we see sanctionable activity, and that is consistent with our policy of economic and diplomatic isolation against Iran,” said Brian Hook, the Direct of Policy Planning for the State Department. Hook suggested that more than 50 international firms have announced their intent to leave the Iranian market, with a special emphasis on energy and banking sectors.

Iran is home to over 9 per cent of proven oil reserves and 18 per cent of proven gas reserves. The way this is playing out, it may not get to realise its full potential if Trump gets his way with intense strong-arm tactics. He is out to close the taps on Iran’s 2.3 million barrels a day of exports. Unlike the two previous US presidents, who allowed for exports of around 1 million barrels a day even under UN sanctions, the current occupant of the White House has no plans for exemptions.

At a conservative benchmark of $60 a barrel, this action would cost Iran just over $4 billion a month.

The US president’s effort will depend in large part on the resistance of Iran’s four biggest customers, China, India, South Korea and Turkey. One of two scenarios could play out with the biggest importer, China. It either resists Washington’s pressure due to Trump’s trade sanctions on Beijing or it caves to offer a payback of sorts to a transactional US president.

Not by chance, Beijing’s imports of US crude rose to a half million barrels a day last month, just shy of what it takes from Iran.

Washington’s high stakes gambit led the Iranians to up the ante in the Vienna talks and at the same time, in the Middle East, by threatening to close off oil tanker traffic in the Strait of Hormuz.

Energy is only part of what are called the snapback US sanctions announced by Secretary of State Mike Pompeo. The first wave will cover industrial products ranging from cars, steel manufacturing, gold and other precious metals. There are nearly $300 billion worth of non-performing loans in a roughly $450 billion (Dh1.65 trillion) economy; interest rates hover around 20 per cent and small and medium-sized businesses are suffering. So too is the average Iranian.

The IMF estimates that due to the dark cloud of US sanctions, Iran may fall back into recession this year from an original growth target of 4 per cent, which was based on the nuclear agreement fostering more investment.

Rouhani and his delegation were also seeking high-profile support in Vienna to help buffer a rising tide of protests back at home, both in the capital of Tehran and in the southwest of the country due to the water shortages. Those who know Iran, took notice when the Bazaari, the powerful merchant class of traders, brought down their shutters to protest the collapsing Iranian rial which has gone from 36,000 at the start of 2018 to around 90,000 on the black market today.

While domestic pressures intensifies, two key Iranian partners, Moscow and Beijing, also remain steadfast in their resistance to unilateral sanctions by the Trump administration and only recognising those imposed by the UN in the past. “The situation is not simple, but we are committed, like China, and other participants in this agreement, to international law,” said Russia’s Foreign Minister Sergey Lavrov.

Trump’s unconventional approach has turned up the heat on multiple burners, with North Korea, Venezuela and Iran all on the boil, making it even more challenging for the Europeans. They are trying to manage an unpredictable US president who not only plans to play hardball against Iran, he has applied similar tactics on the EU as well.

John Defterios is CNNMoney’s Emerging Markets Editor.