United Nations — The United Nations is running a deficit of $230 million, Secretary General Antonio Guterres said on Monday, and may run out of money by the end of October. In a letter intended for the 37,000 employees at the UN secretariat and obtained by CBS News' Pamela Falk, Guterres said unspecified "additional stop-gap measures" would have to be taken to ensure salaries and entitlements are paid.

"Member States have paid only 70 percent of the total amount needed for our regular budget operations in 2019. This translates into a cash shortage of $230 million at the end of September. We run the risk of depleting our backup liquidity reserves by the end of the month," he wrote.

To cut costs, Guterres mentioned postponing conferences and meetings and reducing services, while also restricting official travel to only essential activities and taking measures to save energy.

Although 129 States out of 193 have now paid their regular annual dues, the most recent being Syria, UN Spokesperson Stéphane Dujarric told correspondents at the regular briefing in New York, others needed to pay "urgently and in full".

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"This is the only way to avoid a default that could risk disrupting operations globally. The Secretary-General further asked governments to address the underlying reasons for the crisis and agree on measures to put the United Nations on a sound financial footing."

Guterres had asked member states earlier this year to up contributions to the world body to head off cash flow problems, but they refused, a UN official told French news agency AFP on condition of anonymity.

"The ultimate responsibility for our financial health lies with Member States," Guterres said.

Not including what it pays for peacekeeping operations, the UN's operating budget for 2018-2019 is close to $5.4 billion, with the United States contributing the largest share at 22 percent.

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As the Council on Foreign Relations explained earlier this year, U.S. contributions are vital to the UN's operations, and cuts to discretionary contributions implemented by Mr. Trump's administration have already forced the UN agency that serves Palestinian refugees to make deep cuts.

The White House has been pushing for a broad reassessment of the U.S. contribution to the UN budget since Mr. Trump took office.