The Saudis are blockading Yemen, a nation that needs to import most of its food to survive. They are directly and intentionally causing a humanitarian catastrophe there. There is not need to blame Iran for this.
The Yemeni rebels are cornered and as any cornered people they will take any help they can, including Iran. But this is not the cause of this. The cause is the Saudi led war and blockade.
And what kick started the war in Yemen? That would be a daddy's boy prince wanting to prove he could win his own war without daddy's help (that went well).
None of which would happen if we didn't really enjoy selling guns to the Saudis, on account of all the money they've taken from us when they sold us oil.
And we'd still be happily selling arms to the Iranian King we installed if they hadn't got sick of it and thrown us out.
So this is on us. All of it.