The US has always been supporting jihadist sunnis. Reagan Presidency was no exception.
Your statement infers that the US supported them because they were jihadist Sunnis. And that is not true.
In the Iran-Iraq war -- a Sunni vs Shiite affair -- we actually helped both sides -- preferring they bleed each other out. But, admittedly, we leaned toward Saddam and Iraq (the "Sunni" side) since we had a big bone to pick with Iran.
And we assisted the mujahaddin against the Soviets on a premise that had nothing to do with their religious proclivities. They were, after all, fighting the Soviets.
But, if we have always favored the "jihadist Sunnis", how do you explain our firm support for the Shah and his Iran -- which was nonetheless Shiite?