PARIS/WASHINGTON (Reuters) - The United States must step up its support for a planned African force to fight Islamist militants in West Africa or it could fail, leaving French troops to carry the burden alone, France’s defense minister said on Friday.

French soldiers prepare their armoured vehicles at the Relay Desert Platform Camp (PfDR) in Ansongo, Mali, October 15, 2017, during the regional anti-insurgent Operation Barkhane. REUTERS/Benoit Tessier

France intervened in Mali to ward off an offensive by Islamist militants that began in 2012, and 4,000 of its troops remain in the region as part of Operation Barkhane where they work alongside 10,000 U.N. peacekeepers in Mali.

France and West African countries are pushing for the creation of a regional force known as the G5 Sahel.

Washington provides bilateral assistance, intelligence and training for regional security operations. But it is cool towards the African force and has pushed back against U.N. support for it.

President Donald Trump’s administration has also come under intense scrutiny over its existing operations in West Africa after an ambush in Niger in early October saw four U.S. soldiers killed by jihadists, in what experts say appears to have been an intelligence failure.

“In the Sahel, France is deploying in a high-intensity environment, with tremendous support from the United States. We are immensely grateful for that support,” French Defence Minister Florence Parly said in a speech at a Washington think tank monitored in Paris.

“But much more needs to be done. We can’t be, and don’t want to be, the praetorian (guards) of sovereign African countries. They must be made able to defeat terror on their own,” she said during a visit for meetings with her American counterpart James Mattis and White House National Security Adviser H.R. McMaster.

“I would be happy if you could help spread the word in the Beltway,” she said in a reference to the U.S. government.

Still, discussion in Washington was focused more on what went wrong with the Niger operation. The deadly incident has become a political football in Washington amid criticism of Trump’s handling of condolence messages to the families of the dead soldiers.

The U.S. military is investigating the incident, and the FBI said it was assisting “as it has done in the past when American citizens are killed overseas.”

Hours after Parly’s visit to the Pentagon, Mattis visited Capitol Hill to meet Senator John McCain, who threatened to issue a subpoena to get information about the ambush in Niger after complaining about being kept in the dark.

After their talks, Mattis acknowledged that “we can always improve on communication,” remarks echoed by McCain, the powerful chairman of the Senate Armed Services Committee.

“We have had our problems and issues. But I’m proud to work with him, and I’m proud of the work that he is doing,” McCain said.

From initial accounts, the 40-member patrol, which included a dozen U.S. troops, came under attack by militants riding in a dozen vehicles and on about 20 motorcycles.

Under heavy fire, U.S. troops called in French fighter jets for air support, but the firefight was at such close quarters that the planes could not engage and were instead left circling overhead.

French aircraft evacuated the wounded, but the body of one of the dead soldiers was recovered by Nigerien soldiers only after two days.

The U.S. military’s Africa Command issued a statement on Friday explaining that the 800 U.S. military personnel in Niger were on a mission supporting African forces.

“The U.S. military does not have an active, direct combat mission in Niger,” it said.

“LONG-TERM” EXIT STRATEGY?

Parly said the G5 Sahel force was meant to bolster the security capacity of Chad, Niger, Burkina Faso, Mali and Mauritania, which are all former French colonies.

French officials see the success of the G5 Sahel as a long-term exit strategy for Paris. For decades, France has mounted military operations in its former African colonies but in recent years it has looked to spread the cost.

Until now the G5 force has only received a quarter of its estimated 423 million euro budget, according to a report by the U.N. Secretary General, who said financing the operation would “remain a significant challenge” for several years.

“It will start its first operations soon. It needs support. The U.N. wants to give support. I hope everyone can become convinced that a robust U.N. assistance is necessary,” Parly said.

French defense officials say they expect the first G5 patrols to begin this month and hope that will provide momentum ahead of a donor conference in December.