Inclusion of Bonds in the market

Each country starts out with a set amount of bonds that increases or decreases in relation to their total output. They can sell these bonds on the market and have a daily cost say 1k or 0.5k and they have durations say from 5-20 days most of these things could be fixed however similar to the spies mechanism. Players who have zero money on duration will see significant drop in resources. Either immediately or gradual until they pay back the loan.