NHS pension taxation in the US

At the time the UK National Health Service pension becomes payable to an individual, a mandatory, one-time lump sum of 3x the annual pension annuity is also paid out to the recipient. This lump sum is tax free in the UK. If the recipient is a US citizen does the United States IRS also treat it as tax free for the purposes of worldwide income?

Hi,
You would need to check with the IRS.
Thank you.