Hi,
If the UK company are using their details, EORI etc, for the export of goods then they are not supplying the US company with these goods in the UK. The sale should be at the zero rate of VAT as long as the criteria are met below:
Conditions and time limits for zero rating
There will of course be a sale between the UK company and the US company but it does not sound like this is taking place in the UK and so the sale is either taking place in transit after exiting the UK or in Malaysia.
Thank you.