Nations have used counterfeiting as a means of warfare. The idea is to overflow the enemy’s economy with fake bank notes, so that the real value of the money plummets. Great Britain did this during the American Revolutionary War to reduce the value of the Continental Dollar. The counterfeiters for the British were known as “shovers,” presumably for the ability to “shove” the fake currency into circulation. Two of the most well-known shovers for the British during the Revolutionary War were David Farnsworth and John Blair. They were caught with 10,000 dollars in counterfeits when arrested. George Washington took a personal interest in their case and even called for them to be tortured to discover further information. They were eventually hanged for their crimes.
It does does represent a weakness. If others can duplicate your currency, then you are not sovereign.