WASHINGTON, Oct. 17 -- The tariffs Congress wrote to squeeze the biggest buyers of Russian oil will not start on Sunday, because President Donald Trump waived them on Friday evening, before the first one could land.

An executive order posted on the White House website sets aside the duties and many of the sanctions in the Russia-Iran sanctions law Trump signed on September 18. It leans on a clause that lets a president suspend the law if he certifies to Congress that doing so serves the national interest, and the order says he has sent that certification. The waivers last until Trump or the secretary of state decide "further action is appropriate."

The text shows how much was parked. Section 2 restates the penalties, including a 500 per...