All three major U.S. stock indexes dropped sharply in Monday morning trading, with investors worried about the uncertainty of tariffs imposed by President Donald Trump on key trading partners and then his refusal to rule out the possibility of a U.S. recession in the coming months. The key Dow Jones average of 30 blue chip stocks dropped more than 1%, with the broader S&P 500 index falling 2 percentage points and the tech-heavy Nasdaq barometer off more than 3 percentage points. The S&P 500 finished Friday with a 3.1% weekly drop, its biggest such decline in six months, and the