China might have sent a spy balloon over the US as a power play to prove it can do what it wants, experts say

• A Chinese spy balloon was detected over the US, the Department of Defense said.
• Spy balloons date back centuries, but still have some advantages today.
• Experts say spy balloons can do things satellites can't, and China may have wanted to get caught. 

The US Department of Defense raised the alarm Thursday about a intelligence-gathering balloon it said it spotted over Montana.