Saudi Arabia on Wednesday said weekend attacks on its critical oil infrastructure were “unquestionably sponsored by Iran” but stopped short of saying the strikes were launched directly from or by the Islamic Republic.

Displaying parts of drones and missiles which were recovered from the attack sites at Abqaiq and Khurais, Saudi defense ministry spokesman Turki al-Maliki showed maps aimed at proving the strikes originated from the north and could not have been launched by Yemen’s Iranian-backed Houthi rebels, who have claimed responsibility.

Twenty-five pilotless aircraft and cruise missiles were used to attack the two sites, Maliki said. He told reporters gathered in Riyadh that the weapons were of Iranian origin but Saudi Arabia was still working to pinpoint the exact launch point. The range and accuracy of the weapons were beyond the capabilities of the Houthis, he added.

“Despite Iran’s effort to make it appear so,” the attack didn’t originate from Yemen, Maliki said. “Data analysis of the attack sites indicate weapons of Iranian origin.”

Iran has denied it was involved in the worst attack in Saudi Arabia’s history and President Hassan Rouhani said earlier Wednesday that his country did not want war.

Just before the press briefing, President Donald Trump said he had decided to tighten U.S. sanctions on Iran following the attacks, which had raised the risk that the key energy-exporting region could slide into a regional conflict. The sanctions announcement and Saudi Arabia’s reluctance to pinpoint Iran as the launch site of the attacks appeared to signal that the threat of major escalation was receding.

While Trump initially said the U.S. is “locked and loaded” to respond, he has since signaled that he isn’t eager for another Middle East conflict.

“I have just instructed the Secretary of the Treasury to substantially increase Sanctions on the country of Iran!” Trump said in a tweet, without giving further details.

Trump has been ramping up sanctions on the Islamic Republic since quitting the 2015 nuclear deal with Iran, including severe restrictions on the ability of Tehran to sell oil.

Iran’s economy is already under severe pressure from existing sanctions, though analysts said there were still a number of potential targets for restrictions, including some in the construction sector, additional companies on the Tehran stock exchange and foundations controlled by the regime or Iranian Revolutionary Guard Corps.

But with the vast majority of Iran’s economy dependent on oil sales, additional sanctions may have little more than a marginal impact.

In comments made immediately after the Saudi briefing, Yemen’s Houthi military spokesman Yehya Saree said some of the drones used were new, with a range of up to 1,700 kilometers, and were launched from three different points inside Yemen. He said the drones fired long-range missiles and warned the United Arab Emirates that it could be also be targeted. The U.A.E. said weeks ago that it was drawing down its role in the Yemen war after four years.

Maliki showed surveillance video purporting to show drones moving in a north to south direction, however. He said Saudi Arabia was working to share the information with United Nations experts.

“We are working as I mentioned to determine the exact position of the launch point,” Maliki said. “Whether it’s been launched from Yemen, launched from somewhere else, those people they will be held accountable, and this is a decision at a political level in our country.”

--With assistance from Josh Wingrove and Dana Khraiche