MUNICH — Sen. Lindsey Graham and a bipartisan group of lawmakers, uniting against a Trump administration idea to withdraw U.S. troops from part of Africa, pushed back during a fiery exchange with Defense Secretary Mark Esper here over the weekend, according to four people present at or familiar with the meeting.

Senators and members of the House met with Esper on the margins of the Munich Security Conference. Graham, R-S.C., and Sen. Chris Coons, D-Del., who are members of the Foreign Relations Committee, led the charge, said the four people, telling Esper that Congress would not support a U.S. troop withdrawal from the Sahel region in Africa and laying out the reasons to keep the troop presence there.

At one point, Graham warned Esper that there would be consequences if the Pentagon withdrew all troops from the region. Graham told Esper that he could "make your life hell," according to the four people. One member present said Graham, Coons and several other lawmakers laid out their case "forcefully."

Pentagon press secretary Alyssa Farah said the quote attributed to Graham was false. "I was in the room and that was never said," said Farah. "The secretary had a productive conversation with bipartisan, bicameral members of Congress on the future of U.S. force presence in West Africa."

Graham told the Washington Post Tuesday that he did not tell Esper he could make his life hell.

An aide to Graham said a person in the room does not recall the senator using those words but said there was "bipartisan agreement and support in the meeting in support of the mission."

While Graham has met often with President Donald Trump and was a key supporter during his impeachment, he has repeatedly criticized Trump administration initiatives to remove U.S. troops from crisis zones.

Last year, NBC News reported that during a meeting on the sidelines of the 2019 Munich Security Conference, Graham had a "tense" and "heated" exchange with Esper's predecessor, Acting Defense Secretary Patrick Shanahan, over Trump's decision to pull troops from Syria.

Officials said that at the 2019 meeting, Graham unleashed expletives at Shanahan and told Shanahan that he should consider him "an adversary."

The Sahel region is a huge expanse of western and north-central Africa just south of the Sahara Desert that extends from the Atlantic coast of Senegal across the continent to the Red Sea coast of Eritrea. It includes several nations plagued by international terrorist groups, including Mali, Burkina Faso, Niger and Nigeria. More than a dozen terrorist groups with links to the Islamic State group or al Qaeda, like Boko Haram and al Shabaab, are operating in the Sahel and other parts of Africa.

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While the U.S. military presence in the region fluctuates, about 1,000 American troops are usually deployed in the Sahel, some at a new drone base near Agadez, Niger. The troops train local forces, provide aerial refueling to French military planes and collect and share intelligence.

Among the reasons to keep U.S. troops there, the members of Congress argued over the weekend, is the small number of troops and overall low cost of the deployments. Graham told Esper that he should be able to find the roughly $50 million to fund the deployments in the more than $700 billion overall defense budget for fiscal year 2020, according to the people with knowledge of the exchange.

Sen. Lindsey Graham, R-S.C., takes part in a panel discussion at the 56th Munich Security Conference in Munich on Friday, Feb. 14, 2020. Christof Stache / AFP - Getty Images

Several members told Esper that leaving would abandon a key U.S. ally, France, whose military has been leading the fight against terrorists in the region while the U.S. acts in a support role.

"Isn't this the exact model the Trump administration is encouraging? Another nation leads while the U.S. supports?" a person present at the meeting asked afterward. "Does the U.S. want to leave a place where it's actually working?"

Trump suddenly decided to pull all U.S. troops out of Syria several months ago, leaving the Kurdish-led Syrian Democratic Forces behind to fight ISIS and the Syrian regime. Trump reversed the decision soon afterward and kept a smaller U.S. military force in Syria in a more condensed area.

The members told Esper that both French and African partners are worried that the U.S. could suddenly abandon them, as well.

Later at the Munich conference, after the exchange with members of Congress, Esper praised the French for their work in the Sahel and said he had spoken with his French counterpart about the possibility of a change in U.S. support in Africa.

"I give the French credit for what they've done in Africa, particularly in the Sahel. They've been the real leaders. They've been reaching out aggressively to get more European partners on board with mixed success, and I fully support that effort," Esper said.

Trump campaigned on bringing U.S. troops home, and his defense secretary has supported removing some troops from Africa, South America, the Middle East and Europe to dedicate more forces to the Asia Pacific region to counter a growing China.

Esper said at the Reagan National Defense Forum in December that he was looking at "all of these places where I can free up troops, where I could either bring them home to allow them to rest and refit and retrain or then reallocate them to Indo-Pacific to compete with the Chinese, to reassure our allies, to conduct exercises and training."

Esper began a review to look at the U.S. military combatant commands all over the world to determine whether resources were distributed to best support the National Defense Strategy, which says Russia and China are the biggest strategic competitors to the U.S. The review is widely expected to result in a cut in the number of U.S. troops in Africa to counter China and Russia elsewhere, with emphasis on sending more U.S. forces to the Asia Pacific region.

After initially telling the lawmakers in Munich that U.S. troops could be withdrawn to comply with the National Defense Strategy priorities, by the end of the meeting Esper reassured the group that he would factor their concerns into the decision-making process and would not make any sudden decisions.

This is not the first time the Trump administration has heard about congressional opposition to a drawdown. Last month, Graham and Coons co-authored a letter urging Trump not to withdraw U.S. troops from Africa. The U.S. has about 7,000 troops in Africa, more than 5,000 of them based at Camp Lemonnier in Djibouti.

"Any withdrawal or reduction would likely result in a surge in violent extremist attacks on the continent," the letter warned. "A withdrawal would also abandon our partners and allies in the region."

In December, Trump signed into law legislation co-authored by Coons and Graham to help stabilize fragile regions and conflict-affected areas. In their letter to Trump last month, the senators said the Sahel and the Horn of Africa were "ripe for U.S. engagement," as laid out in the new law.

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The debate over troops in Africa comes as Trump prepares to face voters in November having fallen short of his promises to end wars and bring troops home.

Trump recently has increased the number of U.S. troops in the Middle East, for instance, by more than he has brought home. Many of the new deployments have been in response to increased tension with Iran. But the president has said publicly and privately to aides that he's eager to draw down the number of troops overseas.

As a candidate, Trump promised to end what he called America's "endless" wars. As president. he hasn't ended any of the wars the U.S. was waging when he took office. He is within reach of a peace deal with the Taliban that aims to wind down the war in Afghanistan, but there is no final agreement yet.

Last week, Trump said in an interview with Geraldo Rivera that he "would like to bring our troops back home."

"It's time to come home," Trump said when asked about a possible deal with the Taliban.