But intentions are not binding contractual conditions. Nor need they lead up to binding contractual conditions. Moreover a letter expressing intent, in its form, does not adequately suggest what the appropriate response should be. Whereas a Request for Quotation / RFQ quite literally is a Request. For a Price Quotation. Hence the document's name, it meaning is expressed by it's name. Hence an appropriate response, for a vendor or supplier, is issuing a a price quote.
Even taken at their word, it doesn't change the fact that they are using documentary procedures that are unusual, and abnormal. Contact any business college, or speak to established traders or people working for large multinational corporations. Talk directly to international bankers on this.