Yes, a 1.5% foreign transaction fee will be applied to purchases made at non-US merchants, regardless of the currency charged.
When you make a purchase in a currency other than dollars, the amount deducted from your account will be converted by Mastercard® International Incorporated to dollars. The exchange rate between the transaction currency and the billing currency used to process international transactions is a rate selected by Mastercard® from the range of rates available in wholesale currency markets for the applicable central processing date, which may differ from the rate Mastercard® itself receives or the government-mandated rate in effect for the applicable central processing date.