U.S. President Donald Trump is reportedly considering pulling the U.S. out of NATO, in the latest threat to America’s allies after their reluctance to help reopen the Strait of Hormuz.

In an interview with The Telegraph newspaper, the president described the 77-year-old defensive alliance as a “paper tiger” and, when asked if he would reconsider the U.S.′ membership of the bloc after the Iran conflict ends, Trump told the paper: “Oh yes, I would say [it’s] beyond reconsideration.”

“I was never swayed by NATO. I always knew they were a paper tiger, and Putin knows that too, by the way,” he said, in comments published Wednesday.

Trump has been angered by European allies’ refusal to send warships to help reopen the Strait of Hormuz, a vital oil and gas maritime passage controlled by Iran, and at their refusal to let the U.S. use military bases to launch attacks against the Islamic Republic.

European leaders see any attempts to reopen the Strait of Hormuz as highly dangerous, as Iran continues to attack tankers in the strait that aren’t deemed to be from “friendly” nations.