When I wrote this essay a few days ago, I was honestly puzzled why we had bombed the Iranian militias.
Today's news cleared up that mystery.

Donald Trump has blamed Iran for supporting and aiding "unspeakable crimes" in Syria under its leader Bashar al-Assad.
Mr Trump, during his speech on combating violent extremism in Saudi Arabia, did not mention Syria's alliance with Russia to carry out air strikes.
Near the end of his speech in Riyadh about forging peace, he argued that Iran had provided Syria with "safe harbour, financial backing and the social standing needed for recruitment [of terrorists]".
"From Lebanon to Iraq and Yemen, Iran funds, arms and trains terrorists, militias and other extremist groups that spread destruction and chaos across the region," he continued.
"For decades Iran has fuelled the fires of sectarian conflict and terror; it’s a government that speaks openly of mass murder, vowing the destruction of Israel, death to America, and ruin for many leaders and nations in this very room.

Germany chimed in with a similar message.
And just in case you weren't seeing a pattern, the Democratic Party mouthpiece, Washington Post, says it's time for a proxy war against Iran.

If successful, the Iranian campaign would drastically reshape the regional security situation, harm the fight against the Islamic State in the nearby city of Deir al-Zour and directly undermine U.S. efforts to train and equip an indigenous Sunni Arab fighting force, which is essential to establishing long-term stability.
In short, it’s a fight that the United States cannot and should not avoid. It’s also an opportunity for Trump to accomplish what his administration says it wants to do in the Middle East: Push back against Iranian aggression and expansionism.
...
Two Syrian rebel groups opened up a front against the Iranian-backed forces about two weeks ago, in response to the Iranian campaign, the rebel leader said. One of them is working directly with the U.S. military. The other is supported by the military operations center led by the CIA and allies in Jordan.
Even absent public acknowledgment from Washington, the rebel groups believe they have tacit support from the United States to prevent Iran and the regime from taking over the area. That belief is uniting rebel groups on the ground, who have long wanted to fight Iran and the regime, in addition to the Islamic State.
Those who support the Syrian opposition in Washington are also noticing a shift in the U.S. approach toward confronting Iran in Syria...
“The United States has two major adversaries in Syria, that is Iran and ISIS. Both represent huge risks to U.S. national security and interests in the region,” said Mouaz Moustafa, executive director of the Syrian Emergency Task Force.
The battle for Syria’s south is on, and the Trump team must decide if the United States will play a decisive role. Trump could fulfill his promises to thwart Iran and bring greater stability to Syria — if he acts fast.

Just to be clear:
If it wasn't for Iran, ISIS would have conquered Iraq, and al-Qaeda/ISIS would have taken Syria.