"While you may not see us here, the work continues."
The Met is struggling to put together a long-term team to work with Harry and Meghan in their new role outside The Firm.
Insiders have revealed there has been "little to no willingness" among protection officers to work for the couple.
One source said: "These jobs are the creme-de-la-creme of being a protection officer. Yet, right now, it's not looking like an attractive prospect to anyone.
"No one wants to move their family between multiple countries. No one is clear what the plan is or where they will be based in the medium to long term."
The US security staff, who are still being vetted by the Met, have replaced the Canadian Mounties tasked with protecting the couple while were living on Vancouver Island.
Security sources said the US guards could cost £800 each per day, with a team of up 10 on a round-the-clock rota.
The Royal Canadian Mounted Police last month announced they would not pay for the couple's protection after they quit the Royal Family, leading Harry and Meghan to speed up their plans to head to the US.
In January, they said on their Sussex Royal website: "It is agreed that the Duke and Duchess of Sussex will continue to require effective security to protect them and their son.
"This is based on the Duke's public profile by virtue of being born into the Royal Family, his military service, the Duchess's own independent profile, and the shared threat and risk level documented specifically over the last few years."
Insiders estimate the cost of their security at around £20million a year.
Royal sources say Harry is "desperate" at the situation in UK after Prince Charles, 71, was diagnosed with coronavirus and the Invictus Games next month were postponed.
But Meghan "is ploughing along with meeting after meeting" in preparation for the launch of their new charity.
A source said: "There are a lot of balls in the air and no one is happy with arrangements apart from Harry and Meghan."
Buckingham Palace and the Met Police declined to comment.
Prince Harry and his wife Meghan will still be protected by Met Police officers after officially leaving the Royal Family and setting up home in America.
The couple declared this week that they had made "privately funded security arrangements" after moving from Canada to California with 10-month-old son Archie.
But the Mirror can reveal the couple's private security will be in addition to officers from the Met Police funded by the UK taxpayer.
US President Donald Trump yesterday tweeted: "The US will not pay for their security protection. They must pay!"
Today the couple posted a farewell message on their Sussex Royal Instagram account.
Describing the world amid the coronavirus pandemic as "extraordinarily fragile," they said: "As we all find the part we are to play in this global shift and changing of habits, we are focusing this new chapter to understand how we can best contribute.