Moody’s Investors Service downgraded Japan’s credit rating Monday, Dec 1, highlighting the challenges facing Prime Minister Shinzo Abe as he tries to stoke inflation and growth, the Wall Street Journal reports.

In explaining its move, Moody’s cited heightened uncertainty over Japan’s ability to cut its fiscal deficit after Abe decided last month to delay an increase in the national sales tax scheduled to take effect next year.

The difficulty of the balancing act facing the Japanese government—fueling growth while acting with fiscal responsibility—was reflected in the lower rating, Thomas Byrne, senior vice president of the sovereign risk group at Moody’s, told reporters in Tokyo after the announcement.

“The government has to in effect put one foot on the brake and another on the accelerator,” he said, according to the Journal.

Moody’s acknowledged that delaying the tax increase “could have merit” if growth and tax revenues rise as a consequence, but said a second factor in its downgrade was uncertainty over whether the government’s growth policies would work in the medium term.

The tax decision also poses risks to Japan’s ability to continue to finance its debt in the future, Moody’s said in a statement.

The Japanese government has said it would try to achieve a primary government balance—meaning tax revenue matches spending, excluding interest payments on government debt—by 2020. Abe said at a debate Monday that his administration would work to develop a concrete plan to achieve that goal.

Standard & Poor’s Ratings Services maintained its Japan rating at AA- with a negative outlook.