US President Donald Trump has signed an executive order targeting the Smithsonian Institution, which operates more than 20 museums and research centres visited by millions yearly in Washington DC and New York City.

The order directs the vice-president to "eliminate improper, divisive, or anti-American ideology" from the institute's museums, centres and the National Zoo in Washington.

It also directs the interior secretary to restore federal properties, including parks, memorials and statues, which "have been improperly removed or changed in the last five years to perpetuate a false revision of history".

The move is part of Trump's effort to shape American culture, in addition to politics.

The order is titled "Restoring Truth and Sanity to American History". It says that Vice-President JD Vance, who became a member of the Smithsonian Board of Regents due to his position in government, will lead the purge.

Trump's order says that Congress should not fund Smithsonian exhibits and programmes that "divide Americans by race". It alleges that the American Women's History Museum, which is in development, plans to "recognize men as women".

It also singles out the National Museum of African American History and Culture, saying that the museum "has proclaimed that 'hard work,' 'individualism,' and 'the nuclear family' are aspects of 'White culture'." The museum opened in 2016 in Washington as former President Barack Obama, America's first black president, was leaving office.

The Smithsonian museums offer free entry to some 15 to 30 million visitors each year. It operates 21 museums in Washington, Virgina and New York.

They include the National Museum of American History, the National Portrait Gallery, the American Art Museum, the National Zoo and more than a dozen others.

The order also instructs Secretary of the Interior Doug Burgum to complete "restorations and improvements" to Independence Hall in Philadelphia. It comes ahead of the 250th anniversary of the signing of the Declaration of Independence, which took place within the building.

Trump has set out to radically reshape American culture, which he says has been contaminated by "woke" left-wing ideology. He has signed several orders that are intended to eliminate diversity, equity and inclusion programmes from the federal government - some of which led to legal challenges.

Shortly after taking office, Trump fired the board of the John F Kennedy Center for the Performing Arts in Washington DC, and installed himself as chairman.

The move led to widespread criticism from actors and directors, causing several to cancel upcoming performances.