Jerusalem has warned the United States and several European countries that Iranian enrichment of uranium beyond 60 percent could trigger an Israeli military strike, Axios reported on Wednesday.

The International Atomic Energy Agency last month confirmed in a report that its inspectors had found “particles” of enriched uranium to 83.7 percent at Iran’s underground nuclear site in Fordow. The report pegged Iran’s uranium stockpile as of Feb. 12 at some 3,760 kilograms (8,289 pounds)—an increase of 87.1 kilograms (192 pounds) since its last quarterly report, in November. Of that, 87.5 kilograms (192 pounds) is enriched up to 60%, just a short technical step away from 90%, or weapons-grade.

However, Axios quotes an unnamed Israeli official as saying that Jerusalem doesn’t consider the small amounts of uranium enriched at 84% purity as a trigger “because Tehran didn’t amass any of the material at that level.”

The official told Axios that Jerusalem was not setting as a “red line” Iranian enrichment to 90%, because Tehran might then begin stockpiling enriched uranium to levels just below that.

Accordingly, the Israeli government has told Western allies that any Iranian progress above the 60% threshold could prompt military strikes against Tehran’s nuclear facilities, according to the report.

Israeli officials believe that this message has been transmitted to their Iranian counterparts.

Axios reported that Israeli Prime Minister Netanyahu and Defense Minister Yoav Gallant asked U.S. Defense Secretary Lloyd Austin during his recent visit to Israel to expedite the delivery of the four KC-46 tankers that Jerusalem purchased from Washington last year. Israel reportedly needs the aerial refueling tankers, set for delivery at the end of 2024, for a possible military strike in Iran.

Austin reportedly told Netanyahu and Gallant that the U.S. would try to deliver the planes earlier but stressed this would be difficult due to American military needs.

Last month, U.S. Under Secretary of Defense for Policy Colin Kahl said that Tehran could produce enough fissile material for a nuclear bomb in less than two weeks, comments that echoed those made in an interview by CIA chief William Burns.

Netanyahu has warned that in the absence of a credible military threat or actual military action, Iran will become a nuclear power.

“The longer you wait, the harder that becomes [to prevent]. We’ve waited very long. I can tell you that I will do everything in my power to prevent Iran from acquiring nuclear weapons. That is not merely an Israeli interest; it’s an American interest; it’s in the interest of the entire world,” he said.