In a memo that John Bolton wrote in August 2017, before he joined the Trump team.
details how the US should coordinate with Israel and Saudi Arabia to build support - domestically and internationally - for a withdrawal from the Iran nuclear deal and a much more aggressive policy on Iran. It specifically mentions "providing assistance" to Khuzestan Arabs - the minority group in Iran that the Ahvazi attack perpetrators claim to represent.
Only a year ago, Saudi Crown Prince Mohammed bin Salman explained in an interview that
"We won't wait for the battle to be in Saudi Arabia. Instead, we will work so that the battle is for them in Iran."
His statement was widely interpreted as a sign that Riyadh would dramatically escalate tensions with Iran and intensify its support for various armed groups opposing the government in Tehran.
Abdulkhaleq Abdulla, an adviser to the Abu Dhabi government, justified the Ahvaz attack on Twitter, arguing that it wasn't a terrorist attack and that "moving the battle to the Iranian side is a declared option". Attacks of this kind, he ominously warned, "will increase during the next phase".
The Ahvaz attack comes only one day after Secretary of State Mike Pompeo issued a strong threat to Iran, declaring it would be held "accountable" if there were any more attacks on US consulates in Iraq. The US consulate in Basra, Iraq, has come under attack in the past week allegedly by Iraqi Shia forces close to Iran. The Trump administration has not presented any evidence that Iran had any involvement in that attack, but has declared that it will attack Iran if any more such attacks take place. However, the Iranian consulate in Basra, in turn, has been attacked several times during this same period, with Tehran laying the blame at the feet of the US (also without clear evidence).