English to Spanish Bus/Financial Economics

Hola,
Es un texto sobre la crisis de la eurozona. Aquí, no sé si "sovereign" se refiere a la "deuda soberana" o a "gobierno".
"it carries the risk of exploding marginal costs of funds to those sovereigns facing rising debt levels"

Aquí, un poco de contexto:
"the blue bonds are a very interesting idea but, in times of crisis, like the one the eurozone is currently experiencing, it would be impossible to limit their volume of issuance to 60 percent of GDP because it carries the risk of exploding marginal costs of funds to those sovereigns facing rising debt levels over the 60 percent "

Muchas gracias de antemano