Donald Trump is proferring a new argument for building his triumphal arch in Washington DC: it will be converted into a “top grade military complex” replete with drone and ammunition storage space and customised sniper facilities on the roof and plaza.

In a post on his Truth Social platform on Sunday morning, Trump claimed that his new plan came at the “strong request” of the US military. He said the 250ft structure would be able to “house, store, and have the rapid ability to use large quantities of sniper ammunition in storage”.

With the hyperbole that is his trademark, the president added that the arch would be unique. “There will be no facility like this anywhere in the world.”

The triumphal arch project has come under widespread criticism for its potential impact on the historic area of downtown Washington DC. Its intended location in a circle close to the Memorial Bridge could interrupt the sight lines of several of the most resonant structures, including the Lincoln Memorial and Arlington National Cemetery which would flank it.

The siting of the structure close to the Ronald Reagan Washington international airport has also prompted questions from Democratic Congress members.

Last week, the National Park Service warned that it could have “adverse effects to historic properties” and called for additional planning before the building work went ahead.

The arch is one of several construction projects that Trump has initiated which he claims are necessary to elevate the visual greatness of the US capital but which critics have slammed as thinly veiled efforts to promote his own legacy. They include the creation of a White House ballroom, the refurbishment of the reflecting pool at the Lincoln Memorial and the renovation of the Kennedy Center.

All those projects have run into big problems, ranging from criticism of their aesthetic qualities, structural difficulties and legal challenges. In the case of the John F Kennedy Center for the Performing Arts, one of the world’s pre-eminent cultural venues, Trump has hinted that he might demolish the property altogether in a fit of pique at the courts blocking the addition of his name to its title.

The White House ballroom, which Trump has also been calling a “military complex”, was beset by legal wrangling until the US supreme court last month said the project could go ahead.

The ground breaking that will kick off construction of the arch is expected to begin this month. Trump has linked it to the 250th anniversary of the Declaration of Independence, and said in Sunday’s post that it would be “by far the greatest” triumphal arch in any of the world’s top cities and capitals.

It will be clad in granite, with three golden statues on top.