Once again the complexity of an international incident must take Pennsylvania into account.

The incident was the recent execution of a Shiite activist sheik in Saudi Arabia. The Saudis beheaded Nimr al-Nimr on Jan. 1 or 2 on a conviction of “seeking ‘foreign meddling’ in Saudi Arabia, ‘disobeying’ its rulers and taking up arms against the security forces.”

Political analysts say the Sunni kingdom’s death sentences was a message to the its Shiite minority and neighbors: Don’t meddle in the affairs of Saudi Arabia.

As with all things Middle Eastern, it’s more complicated than that. The slain cleric al-Nimr presented a stunning reality that Saudi Shiites were tiring of their second-class status and might seek autonomy. And in period of waning economic might and prestige, the Saudi leadership must take seriously the threat of a break-away by its Shiite eastern region.

But there’s a deeper repercussion, and this is where Pennsylvania fits into the puzzle.

For the past couple of years the Organization of Petroleum Exporting Countries — OPEC, led by chief oil exporter Saudi Arabia — has responded to the Marcellus Shale gas boom by increasing its own production. The logic is that Saudi Arabia can produce and market energy more cheaply than Pennsylvania and other U.S. oil and gas producers.

The strategy is working, sort of. But the byproduct is worldwide glut of energy resources that has undercut the Saudi economy more than the U.S. economy.

The added impact is that the U.S. is far less dependent on Saudi oil than it was before the Marcellus boom.

The reduction of prestige frightens the Saudi princes more than the loss of market share. Their fears are only heightened by the recent U.S.-Iranian nuclear arms agreement, which signals a shift in the Mideast power structure.

One expert in U.S.-Iranian affairs has called Nimr’ execution a deliberate provocation.

“It is difficult to see that Saudi Arabia did not know that its decision to execute Nimr would not cause uproar in the region and wouldn’t put additional strains on its already tense relations with Iran,” wrote Trita Parsi, an Iran-born American scholar and author, for the Reuters news agency.

Iran’s predominantly Shiite population bitterly protested Sheik Nimr’s execution. They burned the Saudi embassy in Tehran.

Iranian President Hassan Rouhani condemned the embassy torching, “though footage shows that Iranian security forces did little to prevent the attack,” Parsi notes.

To put it more directly, Saudi Arabia thumbed its nose at Iran and the United States as if to say, we don’t need you or your approval.

None of this might have happened had it not been for the rise of American energy independence, driven by the new Marcellus Shale gas industry and hydraulic fracking. It’s akin to the “butterfly effect” — the idea that small events can lead to grand consequences.

It’s something to at least consider as we decide to what extent Marcellus gas should be subjected to state tax.