Did a "false flag" draw the U.S. into WWII ?

A "false flag" is one type of "black ops":

The contemporary term false flag describes covert operations that are designed to deceive in such a way that activities appear as though they are being carried out by entities, groups, or nations other than those who actually planned and executed them.

A recent article at the Daily Beast asks whether a terror attack at the World's Fair in 1940 was designed to get the United States involved in WWII.

On June 4, 1940, Nazi Germany shoved the last British troop off the Continent at Dunkirk. Adolf Hitler moved his forces into position for a final cross-Channel invasion and occupation of England. That same month the new British Prime Minister, Sir Winston Churchill, dispatched a shadowy figure, Sir William Stephenson—later most famous as the original of Ian Fleming’s James Bond, Agent 007—to set up a spy shop for Britain’s MI6 in Midtown Manhattan. A hero of World War One and self-made multi-millionaire, Stephenson was on neutral ground in America, but he and Churchill shared the conviction that nothing was more important to their nation’s chances for survival than winning American support for the war against Hitler. Then, on July 4, 1940, with throngs of holiday visitors at the New York World’s Fair, a time bomb planted in the British Pavilion exploded, instantly killing two New York City policemen and badly mauling five others. Was Stephenson behind the blast in an attempt to frame Nazis and their American sympathizers? Were these officers sacrificed to win American sympathy and draw a reluctant United States into the Second World War?

The article is inconclusive and presents no new evidence.  Posted because we are again in an era where everyone needs to be aware of the possibility of false flags with regard to both international and domestic terrorism.