At first, when it announced the terms of its "oil freeze" agreement with Russia one month ago, Saudi Arabia seemed willing to grant Iran a temporary exemption from the supply freeze, at least until it recovers its pre-embargo production levels. That however changed on Friday when the country's Deputy Crown Prince Mohammed bin Salman, shocked Saudi Arabia's Arab allies in the Persian Gulf, telling Bloomberg his country would only join the freeze curbe Iran - and all other OPEC member nations - also joined.

Following the Friday announcement, yesterday Iran's oil minister Zangadeh made it clear that the country rejects Saudi demands, and would continue ramping up production at will, in the process making the April 17 Doha meeting meaningless.

And then, in a new and unexpected retaliation by Saudi Arabia for Iran's intransigence, moments ago the FT reported that Saudi Arabia has taken steps to slow Iran’s efforts at increasing oil exports, banning vessels that transport Iranian crude from entering their waters, according to traders and shipbrokers.

More details from FT:

Iranian vessels carrying the country’s crude are restricted from entering ports in Saudi Arabia and Bahrain, according to a circular sent by a shipping insurance company to its members in February. The notice said ships that have called to Iran as one of its last three ports of entry will also require approval from the Saudi and Bahraini authorities before entering their waters. Shipbrokers and traders have relayed the same messages since. Iranian oil executives have expressed their concern about the message circulating in the market, saying it is only adding to problems they face in selling their crude. Saudi Aramco, the state oil company, and The National Shipping Company of Saudi Arabia (Bahri) did not respond to requests for comment.

It is not clear just how much of an impact this escalation will have because as shown in the map below, Saudi territorial waters are hardly a major factor in Gulf shipping lanes.

However, considering that Iran already faces insurance, financing and legal obstacles despite the lifting of sanctions linked to its oil industry in January, and considering the amount of clout the Saudis have with financial partners, its attempt to make Iran's oil production more difficult will surely reap at least partial success.

Indeed, as the FT adds, oil tanker association Intertanko and other industry participants say no formal notice has been given by Saudi Arabia but uncertainty is making some charterers less willing to lift Iranian crude.

”It’s seen as an unknown risk,” said one shipbroker. “No one wants to disrupt their relationship with the Saudis.”

As a reminder, the amount of oil being stored at sea off the coast of Iran has risen by 10 per cent since the start of the year, data from maritime data and analytics company Windward show, and now stands at more than 50m barrels.

But what is perhaps far more troubling for Iran is that on Friday president Obama criticized Iranian leaders for undermining the “spirit” of last year’s historic nuclear agreement, even as they stick to the “letter” of the pact.

According to the Hill, in comments following the Nuclear Security Summit in Washington, Obama denied speculation that the United States would ease rules preventing dollars from being used in financial transactions with Iran, in order to boost the country’s engagement with the rest of the world.

Instead, Obama claimed, that Iran’s troubles even after the lifting of sanctions under the nuclear deal were due to its continued support of Hezbollah, ballistic missile tests and other aggressive behavior. “Iran so far has followed the letter of the agreement, but the spirit of the agreement involves Iran also sending signals to the world community and businesses that it is not going to be engaging in a range of provocative actions that are going to scare businesses off,” Obama said at a press conference. “When they launch ballistic missiles with slogans calling for the destruction of Israel, that makes businesses nervous.” “Iran has to understand what every country in the world understands, which is businesses want to go where they feel safe, where they don’t see massive controversy, where they can be confident that transactions are going to operate normally,” he added. “And that’s an adjustment that Iran’s going to have to make as well.”

And so a new potential bullish catalyst for oil emerges: If Obama's anger grows, and if the Iran agreement is ultimately unwound, that would mean that all of the excess oil brought on market by Iran, would promptly be taken off the market once more, in the process eliminating the supply glut overnight.

It remains to be seen if Obama is ready to sacrifice his foreign "legacy" just to boost the price of oil, and thus, gas at the pump. Then again, considering over the weekend Goldman made a huge U-turn on the "low oil is good for the economy", and if Obama's advisors start whipsering in his ear how higher oil prices are critical for US energy companies, that may be precisely what ends up happening.