BERLIN, April 18 (Xinhua) -- NATO Secretary General Mark Rutte dismissed concerns over a potential U.S. withdrawal from the alliance in an interview published Saturday.

In an interview with the German newspaper WELT AM SONNTAG, Rutte said he does not see the United States leaving NATO, but stressed the need for a stronger Europe within a stronger alliance.

The remarks came amid tensions fueled by recent comments from U.S. President Donald Trump, who complained that European allies were unwilling to support the war with Iran, called NATO a "paper tiger," and said he was considering withdrawing from the alliance.

Trump is visibly disappointed with some NATO members, Rutte said, adding that he understands the U.S. president's frustration, and reaffirming that the U.S. nuclear umbrella remains the "ultimate guarantor" of European security. ■