a govt can't print money anymore - they used to be able to, but the creation of the rothschild/morgan federal reserve system implemented the world over has removed the right of money creatio away form the people and into the hands of a select few.
Treasuries and Federal Banking Reserves are two very different entities.
in the USA, the US treasury raises capital by selling bonds that the Federal Reserve buys, because no-one else will unless mandated, like their superannuation 401k funds etc.
in Australia, people (the wider "market") still see our bond yields as an attractive return on a relatively lower risk market (that market being GDP, Taxation, etc). therefore, when we issue bonds, the world buys them, not the RBA.
so countries can only issue bonds out the wazoo and hope that they're bought, the interest payment on these are our "debt obligations". in the USA, the Federal Reserve says "...your "economy" (read Dow Jones) is falling, you need to issue bonds so that we can buy them to prop your "economy" up...."