America did not share with the UK the details of the peace deal signed by former US president Donald Trump with the Taliban in Doha in 2021 that marked the end of the 20-year presence of US troops in Afghanistan.
Washington's decision to keep London out of loop on a classified annex to the Doha agreement signed in February 2020 placed a significant strain on the UK-US 'special relationship' said senior UK figures, reported The Sunday Times.
The revelation is the latest in a series of criticisms over the handling of the withdrawal of western powers from Afghanistan last year.
A scathing report earlier this year by MPs described chaotic efforts to withdraw UK nationals and the local personnel who worked with them from the country as a “disaster”. It also said they were a “betrayal” of allies that would damage British interests for years to come.
Mr Trump's peace accord with the Taliban in Qatar was part of the former president's pledge to stop "forever wars" and end the conflict that had persisted for two decades.
The agreement restricted fighting for both US and Taliban forces and paved the way for the full withdrawal of American troops in return for counter-terrorism guarantees.
It also included secret annexes understood to contain details on operational procedures. However, interviews conducted by The Sunday Times with UK government sources revealed that those annexes were never shared with Britain or Nato partners.
The British newspaper reported that, after months of being kept in the dark, the chief of the defence staff at the time, Gen Sir Nick Carter, approached his US counterpart General Mark Milley to ask for a briefing.
A senior minister said it was "extraordinary" that it took "military to military" to "get the information out". He added that it put a "massive strain on the operational aspect of the special relationship", as well as affecting the "level of trust" between the two western powers.