UNITED NATIONS (AP) — Secretary-General Antonio Guterres is urging strong international support for a 5,000-strong force to fight the growing threat from extremists in Africa's vast Sahel region, warning that if urgent action isn't taken "the stability of the entire region, and beyond, is in jeopardy."

The U.N. chief said in a report obtained Monday by The Associated Press that the security situation in the Sahel is in "a continuous downward spiral" and stressed that inaction will leave millions of people at risk of violence.

"Ultimately, we, the international community, will bear the responsibility for such a disastrous scenario," Guterres said.

In February, the leaders of Mali, Mauritania, Niger, Burkina Faso and Chad agreed to establish the force to combat terrorism and transnational organized crime, help restore government authority throughout the countries, return millions of refugees and displaced people, and facilitate humanitarian aid.

The 22-page report paints a grim picture of the situation in the region today.

"The Sahel region is now trapped in a vicious circle where poor political and security governance, combined with chronic poverty and the effects of climate change, have contributed to insecurity," Guterres said. "The rise of terrorism and lawlessness has further undermined state authority, leaving governments unable to provide for and protect their citizens, which in return contributed to radicalization and further instability."

Today, some 4.9 million people across the Sahel have been forcibly displaced, "demonstrating the toll of conflict and violence in the region," he said. And in the broader region that also includes Cameroon, Nigeria and Senegal "some 24 million people are in need of life-saving assistance."

The operational plan for the so-called G5 joint force calls for strengthened border security in the first phase and "the deployment of a full-fledged force, operating across the entire Sahel to neutralize armed terrorist groups and criminal organizations" in the second phase by March 2018, Guterres said.

But funding has become a critical issue.

The Security Council unanimously adopted a resolution in June welcoming the deployment of the G5 force, but at U.S. insistence it did not include any possibility of U.N. financing. The African Union Peace and Security Council has authorized its deployment for an initial 12-month period.

Guterres said primary responsibility for mobilizing resources to support the force lies with the five countries that are contributing the troops.

The G5 states have developed a budget estimated at 423 million euros to establish the joint force, including its first year of operations. But Guterres said only a quarter of that amount has been pledged.

He said a donor conference will be held in Brussels on Dec. 16, stressing that "bilateral support to G5 countries' national armed forces and security services will remain critical."

Guterres said he also remains "fully committed to providing the entire range of support of the United Nations to the region" and said the establishment of the G5 force "represents an opportunity that cannot be missed."

The secretary-general outlined four options for U.N. support to the joint force.

He said the Security Council has previously approved logistical support for non-U.N. missions in Sudan and Somalia, and the U.N. has identified four options through which the U.N. can use assessed contributions from the 193 U.N. member states to support African Union peace operations.

These range from the least ambitious, which would use the existing Security Council mandate for the U.N. peacekeeping force in Mali to support its defense and security forces, to expanding the Mali mission's mandate, to establishing a U.N. office to provide limited support to the G5 force that would include medical assistance, food, fuel, water and other supplies and technical help.

The most ambitious option would expand the assistance a U.N. support office would provide to include maintenance contracts, satellite imagery, telecommunications and information technology, and infrastructure support as well as other items.

Guterres expressed hope the Security Council's visit to the Sahel starting later this week will give members "an opportunity to garner further insight into the situation on the ground and understand the urgency of supporting the joint force."

On Oct. 30, the secretary-general will present the report's recommendations to a ministerial meeting of the council chaired by French Foreign Minister Jean-Yves Le Drian.