Former US vice president Dick Cheney and former American secretary of state Henry Kissinger are expected to attend Margaret Thatcher's funeral on Wednesday.
Cheney is seen as one of the main architects of the 2003 Iraq War as well as being the driving force behind the George W. Bush's 'War on Terror' which saw the creation of the Guantanamo Bay prison camp and the waterboarding of suspects.
Kissinger, the powerful former national security adviser and secretary of state to presidents Richard Nixon and Gerald Ford, is also a controversial figure.
For some he is credited with bringing about the end of the Vietnam war as well as opening up relations with China. However he has also been accused of war crimes for playing a key role in the illegal bombing of neutral Cambodia.
Following her death Kissinger said Thatcher made "an enormous difference" as British prime minister and described her as a "breath of fresh air".
Cheney and Kissinger will be joined by other conservative Republicans from the United States at the funeral. On Monday the US House of Representatives announced it was sending three Republican members of congress to London.
Among them is Minnesota congresswoman Michele Bachmann, who sought the Republican nomination for president in 2012.
Bachmann is known for her ultra-conservative views including describing homosexuality as "part of Satan".
In 2012 the congresswoman alleged the fact Hillary Clinton had a Muslim aide showed there was a "deep penetration" of the Muslim Brotherhood into the Obama administration.
Joining Bachmann will be Marsha Blackburn and George Holding of North Carolina. Also attending the funeral is the former Republican speaker of the House of Representatives, Newt Gingrich.
The conservative former congressman who was a candidate for the Republican presidential nomination in 2012 is a big fan of Thatcher.
Following news of her death on Monday, Gingrich said he could not remember an occasion over a 20-year period where being with her "failed to instruct, inspire and educate".