President Trump's anti-Iran strategy increasingly looks like it's facing its greatest test, while his White House waits for a new national security adviser.The state of play: Evidence out Monday indicates Iranian weapons were used in Saturday's attacks on major oil facilities in Saudi Arabia, which sent oil prices soaring.Iran denies responsibility for the airstrikes. Iranian President Hassan Rouhani said Monday the attack on Saudi Arabia’s Aramco oil facilities was a reciprocal measure by "Yemeni people" to assaults on this country, per Reuters.The Saudis say the attacks weren't from Yemen, where the country's Iran-backed Houthi rebels initially claimed responsibility.The big picture: "The assault ... has highlighted what analysts say is a rapidly evolving threat from Iranian-made weapons in the region, marking a potentially alarming shift toward precision strikes on critical infrastructure," the Washington Post reports."The same strategic logic that animates Iran’s missile program is evident in its drone program: it enables Iran to operate from range, keep its territory safe and strike at far away targets,” said Behnam Ben Taleblu, a senior fellow at the Foundation for Defense of Democracies.Between the lines: The Iranians are attempting to apply pressure on the U.S. and its allies by creeping out of the 2015 nuclear deal and by creating havoc in the region, Axios' Dave Lawler emails.Iran has rejected the possibility that Rouhani would meet Trump on the sidelines of the UN General Assembly meeting next week, according to the New York Times. Iranian officials insist they won’t sit down with Trump until he loosens sanctions.Trump continues to express interest in talks, while in the meantime standing by his "maximum pressure" approach. Iran's Supreme Leader Ayatollah Ali Khamenei said early Tuesday, "There will be no talks with the US at any level," per AP.What he's saying: In the Oval Office Monday, Trump said "it would look to most like it was Iran" that was responsible the attack. The president has said that the U.S. is "locked and loaded," while insisting the U.S. is insulated from disruptions to the oil supply and he wants to avoid a military conflict with Iran if possible.By the numbers: "Brent crude futures, the global gauge of oil, soared 15% to $69.02 a barrel [Monday], the largest-ever percentage gain for the front-month contract on a closing basis," the WSJ reports.The bottom line: As we saw over the weekend, until this dynamic changes, expect more escalation.Go deeper: U.S. strike on Iran could bring tangle of escalation risksEditor's note: This article has been updated with comments from Iranian President Hassan Rouhani and Supreme Leader Ayatollah Ali Khamenei.