Neither the Ukraine war nor the Gaza war set off World War 3, but I think the situation with the 3 US soldiers getting killed in Jordan might. First think about what happened. The US army had a base in the middle east, where they have no business being, and some guys there decided they don't like having American soldiers in their neighborhood and decided to kill some of them. The charge is that these guys received money from Iran at some point, and therefore Iran is responsible for the killings. Iran denies responsibility for the killings. America says it will now retaliate by killing Iranian soldiers. Iran says it will retaliate back if America does this. If all this happens, which seems likely, then a war between the US and Iran will surely break out.