Apparently their strategy of dumping oil on the world market below market prices is having an adverse affect on Saudi Arabia's budgets. Contributing to the budget shortfalls is a costly war with Yemen. As a consequence this rich nation is having to borrow billions--the author doesn't report from where, but likely this is from Western banks and institutions.
Over the past year, Saudi Arabia – once among the richest nations on the planet – has wound up having to sell some $4 billion in bonds. It has been necessary in order to maintain levels of spending on public works and continue financing the war against Yemen. The Saudi government has also had to draw on its reserves of foreign currency. Falad al-Mubarak, who heads the Saudi Arabian Monetary Agency (the nation’s equivalent of the U.S. Federal Reserve), predicts “an increase in borrowing” in the face of a projected $130 billion deficit.
The primary cause is the drastic decline in the price of crude oil.