Invitation letter for training organized by UK company at USA

[sambasiva]

I have valid Business Visa and wish to attend training at USA by UK company. My question here , does invitation letter by UK company can be shown to Immigration officer at Port of Entry with valid training dates . UK company mentioned local venue and its contact phone in letter. I wish to know does UK company letter is suffice to show to immigration officer at port of entry. Please enlighten me how to proceed.
Thanking you for your help.