He faced questions on the possibility of launching an inquiry into the 20-year war in Afghanistan, which saw hundreds of UK personnel suffer life-changing injuries and more than 450 deaths recorded.
Asked about the potential for an inquiry, the Prime Minister told MPs: “The people of Afghanistan have been the beneficiaries of decades of UK support and investment.
“If you ask me whether I feel happy about the current situation in Afghanistan, of course I don’t.
“I’m apprehensive, I think that the situation is fraught with risks.
“We have to be absolutely realistic about the situation that we’re in and what we have to hope is that the blood and treasure spent by this country over decades in protecting the people of Afghanistan has not been in vain and that the legacy of their efforts is protected.”
He said he would make a statement to the Commons on Thursday, adding: “On the matter of the inquiry, you’re ahead of us there.”
Liaison Committee chairman Sir Bernard Jenkin said that the servicemen and women who had lost their colleagues would want to know that lessons were being learned and implemented.
Mr Johnson replied: “We learn the lessons the whole time. But if you are asking me to extemporise an announcement now about an inquiry into Afghanistan, I’m not going to do that.”
In April, US President Joe Biden announced the remaining 2,500 US troops would leave by September 11 – the 20th anniversary of the 9/11 terrorist attacks on America.
Other Nato allies then confirmed they would follow suit, including the UK – which in May began withdrawing its remaining 750 military trainers.
Defence Secretary Ben Wallace previously said Britain had been put in a “very difficult position” to continue the mission once the US announced its decision to leave.