The Federal Reserve’s own website states this clearly.
“As the nation's central bank, the Federal Reserve derives its authority from the Congress of the United States. It is considered an independent central bank because its monetary policy decisions do not have to be approved by the President or anyone else in the executive or legislative branches of government, it does not receive funding appropriated by the Congress, and the terms of the members of the Board of Governors span multiple presidential and congressional terms.”
As we all know, the US government takes in taxes every year from people and businesses, but when the government wishes to spend more money than it has (which is always), it has to ask the Federal Reserve for a loan. The U.S. government gives U.S. Treasury bonds to the Federal Reserve, and the Federal Reserve gives the U.S. government "Federal Reserve Notes" in return (the same type of notes you have in your pocket right now). Happy days, now the government can keep ramping up its military spending indefinitely. But as with everything in life that seems too good to be true, it comes at a price. But don’t panic too much, it’s only you and I that lose out.