The U.N. Security Council unanimously approved a resolution Thursday welcoming the deployment of a 5,000-strong African force to fight the growing threat from extremists in the vast Sahel region after it was watered down to meet U.S. demands.

France's U.N. Ambassador Francois Delattre called it "a landmark resolution" that brings "strong and decisive support" from the U.N.'s most powerful body to the five countries contributing troops — Mali, Burkina Faso, Mauritania, Niger and Chad.

The United States is trying to cut $1 billion from the U.N. peacekeeping budget and wanted to ensure that the measure did not open the possibility of new costs.

So the final resolution eliminated several key provisions that would have given teeth to the measure: It got rid of the reference to Chapter 7 of the U.N. Charter, which would have made the measure militarily enforceable; it replaced U.N. authorization for the deployment with a welcome; and it dropped a request for the U.N. secretary-general to come up with options for financing the force.

Despite the absence of Chapter 7 authorization, Delattre said unanimous backing for the resolution brings "maximum political support" to the force, "and maximum support means maximum mobilization at the side of our African countries."

"With this text we open a new chapter in our partnership with Africa," he said. "So there is a strong dynamic, a strong momentum that will come out of this resolution."

The presidents of the so-called Group of Five countries agreed in February to set up a joint force to combat extremist groups in the region. The U.S. said no U.N. authorization was necessary for the force to deploy, but France stressed that the African Union and the five presidents asked for U.N. backing.

Mali's U.N. Ambassador Sem Konofourou, speaking on behalf of the G5, said the council is sending "a clear message of the firm stand of the international community against terrorist groups, which came together recently to further destabilize our region," and a message of solidarity with the people of the Sahel.

He said the G5 force will enable the countries "to pool their efforts and their means to effectively fight terrorism, organized crime and trafficking in persons, which nowadays is a true threat to international and regional peace and security."

The resolution urges the G5 force to coordinate and exchange information with France's Operation Barkhane, which has about 4,000 soldiers fighting extremists in the five countries, and the more than 12,000-strong U.N. peacekeeping force in Mali.

Most of the West African extremist groups being fought by France trace their origins to al-Qaida's North Africa branch. But extremists linked to the Islamic State group and Boko Haram have also moved into the Sahel and carried out attacks.

The resolution "welcomes the deployment" of the G5 force "with a view to restoring peace and security in the Sahel region." It urges the countries to continue efforts toward the force's "sustainable, viable and effective operationalization."

Council members expressed continuing concern at "the transnational dimension of the terrorist threat in the Sahel region" as well as serious challenges from transnational organized crime including trafficking in arms and drugs and smuggling of people including migrants.

On financing, the resolution states that the five countries have the responsibility for providing the force "with adequate resources."

It welcomes the European Union's contribution of 50 million euros and "encourages further support from bilateral and multilateral partners." It also encourages supporters "to expeditiously convene a planning conference to ensure coordination of donor assistance" to the force.

The resolution asks Secretary-General Antonio Guterres to present an oral report on the activities of the G5 force in two months — "including on its operationalization, on challenges encountered and possible measures for further consideration" — and a written report within four months.