This was the first time that the United States was directly involved in another country. And so it was the beginning of United States foreign policy.
This is from the White House Historical Association’s Facebook page: https://www.facebook.com/WhiteHouseHistory/?fref=nf
“For the first time, the White House became a communications center in wartime during the Spanish-American War of 1898.
When the ship U.S.S. Maine exploded in Havana Harbor on the evening of February 15, President William McKinley received a telephone call at 3:00 a.m. Immediately, the president established a special telegraph office control center on the second floor of the White House called the “war room.” The office allowed McKinley to contact the army and navy. Pins stuck into maps recorded the movements of troops and supplies.
The war, which lasted only three months, was a major victory for the United States, and French ambassador Jules Cambon commented that “much of the rapid success of the United States” was due to the communication equipment available to the president.”