Saudi Arabia said it would show evidence on Wednesday, September 18 linking regional rival Tehran to an unprecedented attack on its oil industry that Washington believes originated from Iran in a dangerous escalation of Middle East frictions, Reuters reports.

Tehran has denied involvement in the Sept. 14 attacks on oil plants, including the world’s biggest crude processing facility, that initially knocked out half of Saudi Arabia’s production.

“We don’t want conflict in the region ... Who started the conflict?” Iran’s President Hassan Rouhani said on Wednesday, blaming Washington and Riyadh for war in Yemen.

Yemen’s Houthi group, an ally of Iran, has claimed responsibility and said they used drones to assault state oil company Aramco’s sites.

Secretary of State Mike Pompeo and other U.S. officials were headed to Saudi Arabia. United Nations experts monitoring sanctions on Iran and Yemen also left for the kingdom, Saudi’s U.N. envoy said.

Concrete evidence showing Iranian responsibility, if made public, could pressure Riyadh and Washington into a response, though U.S. President Donald Trump said he does not want war.

The Saudi Defense Ministry said it will hold a news conference on Wednesday at 1430 GMT to present “material evidence and Iranian weapons proving the Iranian regime’s involvement in the terrorist attack”. Riyadh has already said preliminary results showed the attack did not come from Yemen.