Final answer:
The statement is false. An increase in imports may raise aggregate demand but not aggregate supply, which could be unaffected or decrease due to competition.
Step-by-step explanation:
The statement 'An increase in imports (independently of a change in the U.S. price level) will increase both U.S. aggregate supply and U.S. aggregate demand' is false. An increase in imports, all else equal, would typically increase aggregate demand (since imports are a component of consumption), but it does not increase aggregate supply. In fact, increased imports may signify an outflow of currency to purchase foreign goods and do not contribute to the U.S. production of goods and services. Therefore, aggregate supply would likely remain unchanged or could even decrease if domestic producers face more competition from foreign goods. This dynamic can be influenced by the relative prices of goods and changes in currency exchange rates.