IHT on my US IRA

I currently have an IRA (Independent Retirement Arrangement) in the USA from when I lived there, but now I'm back in the UK. The IRA is just like a SIPP - except it's held in the US. Will it be excluded from my estate and therefore IHT (just as a SIPP would be) if I passed away tomorrow?

Hi,

Please contact our Inheritance Tax team for advice.

Inheritance Tax: general enquiries 

Thank you.