The president made the exciting announcement on Twitter at the end of February.
President Trump has been trying to hold a military parade since his inauguration. According to the New York Times, Trump's interest in military parades peaked after attending the Bastille Day parade in France.
The American president, who has a fascination with displays of military strength, had hoped to have tanks and jets at his own inaugural parade, but he was told he could not. So the Bastille Day parade seemed like a natural fit for Mr. Trump, who sometimes appears bored at public events but who seemed transfixed at the performance in Paris.
...Mr. Trump’s joy appeared to crest when warplanes made their appearance. He could be seen gesticulating and whispering to Mr. Macron as an array of jets thundered past, including one leaving trails in the colors of the Frencc
The president tried to hold a parade in celebration of Veterans Day before that plan was quashed. The president maintained a parade would be beneficial for the country. Per CNN:
President Donald Trump said in February that a military parade in Washington would be "great for the spirit of the country," but that it would need to come at a "reasonable cost." The President said he was inspired by the Bastille Day parade in France, which he described as "quite something" after attending in 2017.
It does appear the president may have found a way to hold his military-focused event—piggybacking onto events already scheduled to take place in Washington, D.C., over the Fourth of July holiday. Per the New York Times:
“A ‘Salute to America’ parade,” the president said at a meeting of his cabinet at the White House. He called it more of “a gathering, as opposed to a parade, I guess you’d have to say.”
However, some already involved with pre-scheduled events resent Trump's insistence on politicizing the holiday.
The New York Times reports previous attempts at parades have been shot down by government officials due to concerns about costs.
Responding in a tweet of her own, Washington’s mayor, Muriel E. Bowser, said she was “the local politician who finally got thru to the reality star in the White House” so that he would understand the “realities” of the expense of the kind of parade he wanted. She estimated it at $21.6 million in city spending alone.
A cost breakdown provided by the city to The New York Times showed that 18 local agencies would share the cost of the $21.6 million price tag, including more than $13 million for the Metropolitan Police Department for security measure.
The New York Times writes that some, including those in the Trump administration, have indicated a distaste for large shows of military force in the American capital.
Jim Mattis, the former defense secretary, objected to having the American military march in lock step down Constitution Avenue, accompanied by tanks and fighter planes. The Defense Department estimated the cost last year for a Veterans Day parade at $92 million, sending the White House into sticker shock and prompting Mr. Trump to fold on his order.