Amid US threats to five Iranian oil tankers that were shipping gasoline to Venezuela in May, Iran was tracking US commercial ships in the Persian Gulf and the Gulf of Oman, preparing to retaliate against those ships if the US made good on threats against the tankers.
It’s not clear that Iran told the US that they were preparing reciprocal operations against American merchant ships. The US ultimately did not militarily confront the Iranian ships, though they did stop two of the ships with threats to deny them insurance because they were legally owned by third-party countries.
US sanctions have prevented Iran from selling oil and gas to most of the world, and the sanctions against Venezuela have brought painful fuel shortages. Iran eased those shortages somewhat, and have said they will send more if Venezuela asks.
The US and Iran remain in a tense state, and both nations remain seemingly ready to retaliate against one another at any time. This has been an ongoing reality in the Persian Gulf, and shows no signs of getting better.