This paper investigates the long- and short-run neutrality of open-market monetary policy in a world of fixed exchange rates and imperfect substitutability between bonds denominated in different currencies. Using an illustrative portfolio-balance model, it shows that when the public discounts the future tax liabilities associated with the national debt and the central bank supports the exchange rate by trading non-interest-bearing foreign assets, open-market policy has a short-run effect, but no long-run effect, on the domestic price level and interest rate. When the foreign-exchange intervention assets earn interest that is rebated to and capitalized by the public, open-market policy loses even its short-run efficacy -- the capital-account offset to monetary policy is complete.