The Great European War posed no national security threat whatsoever to the US. And that presumes, of course, the danger was not the Entente powers—but Germany and its allies.
From the very beginning, however, there was no chance at all that Germany and its bedraggled allies could threaten America—-and that had become overwhelmingly true by April 1917 when Wilson launched America into war.
In fact, within a few weeks, after Berlin’s Schlieffen Plan offensive failed on September 11, 1914, the German Army became incarcerated in a bloody, bankrupting, two-front land war. That ensured its inexorable demise and utter incapacity in terms of finances and manpower to even glance cross-eyed at America on the distant side of the Atlantic moat.
Likewise, after the battle of Jutland in May 1916, the great German surface fleet was bottled up in its homeports—-an inert flotilla of steel that posed no threat to the American coast 4,000 miles away.