Abu Dhabi (CNN Business) Coordinated strikes on key Saudi Arabian oil facilities, among the world's largest and most important energy production centers, have disrupted about half of the kingdom's oil capacity, or 5% of the daily global oil supply.

Yet key questions about the attacks remain unanswered. US Secretary of State Mike Pompeo pinned the strikes directly on Iran, which backs the Houthi rebels. But he said there was "no evidence the attacks came from Yemen."

Preliminary indications are that the attacks likely originated from Iraq, a source with knowledge of the incident told CNN. Iran wields significant influence in southern Iraq, which is situated much closer than Yemen to the affected Saudi sites.

"Iran has now launched an unprecedented attack on the world's energy supply," Pompeo said in a Twitter post.