Last week, the UN World Food Program said Yemen is on the brink of “ full-scale famine ,” and classified 7 million people in the country as “severely food insecure.” Scott Paul, a senior policy adviser at Oxfam, said, “The likeliest scenario for the Hodeidah operation, involving a lengthy or indefinite closure of the port, would precipitate famine in parts of Yemen over a matter of months, costing many thousands of lives.”

Many of Yemen’s cities and towns have been decimated in the two-year conflict, which began after Houthi rebels seized the capital of Sanaa and other cities. A Saudi-led bombing campaign to dislodge the rebels and fighting on the ground has resulted in at least 10,000 deaths and major food shortages.

It’s unclear where that four-to-six–week figure came from. One senior Pentagon official who wasn’t present at the meeting told BuzzFeed News that such expectations were unrealistic — and that retaking the port “could take months.”

But aid groups view that forecast as wildly optimistic and fear the Pentagon is attempting to understate the complexity of the mission in order to win support for it inside the Trump administration.

During the meeting on Thursday, convened at the request of aid agencies, a Pentagon official tried to ease those concerns by floating the possibility that the operation could be “clean” and result in the Saudis taking full control of the port in “four to six weeks.”

The Defense Department is in favor of providing logistical and intelligence support for an ambitious operation led by the UAE military to retake the Houthi-controlled city of Hodeida. But key bureaus inside the State Department and the US Agency for International Development oppose the initiative, believing it will trigger a full-blown famine in the country by closing the port where most of the humanitarian aid in the impoverished country enters.

The Pentagon advanced its case for a controversial US-backed military assault on a strategic port city in Yemen last week to a room of State Department officials and skeptical humanitarian aid groups, BuzzFeed News has learned.

Jamal Mujalli al-Mashriqi, 4, who suffers from malnutrition, sits on a bed at a hospital in the northwestern Yemeni city of Saada.

The governments of Saudi Arabia and the UAE want to control the Hodeida port because it is an entry point of supplies to Houthi militants — an Iranian-backed rebel movement that the Saudi-led coalition has been fighting for two years.

Many officials inside the Pentagon, including Secretary of Defense James Mattis, view support for the Saudi coalition as fulfilling President Donald Trump’s directive to push back against Iranian influence in the Middle East.

Last month, the National Security Council scheduled a meeting to address a memo sent by Mattis to the White House saying that “limited support” for the Hodeida operation would help push back against a “common threat,” the Washington Post reported.

The meeting of US officials and aid groups last week took place at the State Department’s headquarters in Foggy Bottom. US officials informed aid groups that their humanitarian concerns were being debated at the highest levels of government. But one aid group left the meeting with the belief that the US is intent on going forward with the operation despite the objections.

The Pentagon declined to comment on upcoming operations.

It’s unclear if Trump will break with his predecessor and authorize the operation. The White House declined to comment on any decisions made during the March NSC meeting. The position of Secretary of State Rex Tillerson is also unclear.

Late last year, Barack Obama’s White House rejected an Emirati proposal to help recapture the Hodeida port due to concerns about the difficulty of repelling well-equipped Houthi rebels and fears that it would exacerbate the already dire humanitarian situation.

At the time, the Pentagon’s push for White House approval failed due to opposition from USAID and some divisions inside the State Department, namely the Bureau of Democracy, Human Rights and Labor and the Bureau of Population, Refugees and Migration.

“USAID has always said this operation would take a country that’s been on a knife’s edge of famine for the past two years and tip it over,” Jeremy Konyndyk, who left USAID as director of foreign disaster assistance in January, told BuzzFeed News.

Other areas of the State Department, such as the Near East Affairs Bureau, are more supportive of the operation, said a former US official.

These same battle lines over the operation exist within the Trump administration, but the interagency power dynamics have shifted significantly.

Trump granted the Pentagon broad authority to conduct operations in the Middle East — and has touted the policy as an important break from the Obama administration. “I authorize my military,” Trump told reporters Thursday as he heralded the Defense Department’s successes in the last eight weeks. “We have given them full authorization.”

Meanwhile, the civilian agencies that previously pushed back against the Defense Department’s proposal are lacking leadership due to vacancies left by Obama-era political appointees. The White House has yet to appoint an administrator for USAID or assistant secretaries for Democracy, Rights and Labor and Population, Refugees and Migration.

“It’s tough when you’ve got USAID without a single political appointee,” said Konyndyk, the former USAID director. “Last time the White House sided with us, but USAID’s ability to advocate in the interagency process is less than what it was.”

When asked if Tillerson backs the view of his subordinates who oppose the operation, a State Department official did not directly address the question. “The U.S. government is concerned about the grave humanitarian situation in Yemen and urges all sides to allow unfettered access for shipments of humanitarian aid and food to the Yemeni people,” the official said. “An enduring solution will come through a comprehensive peace deal, which will require compromise from all sides, for the good of the Yemeni people.”

In the two years of fighting, both the Saudi-led coalition and the Houthis have been blamed for holding up aid shipments intended for malnourished civilians. But aid workers said crucial aid shipments are still moving through Hodeida, though that is not likely to continue if a military operation is undertaken.

When the Saudi coalition recaptured Aden in 2015, humanitarian aid couldn’t get through the port for four months. Aid experts and military analysts fear the Hodeida operation could result in even longer delays.

“The real issue is that even if the operation goes well, aid is still not going to pour into northern Yemen since the al Houthi-Saleh forces will continue to hold the roads, making distribution of the aid a challenge,” said Katherine Zimmerman, a Yemen analyst at the American Enterprise Institute.

“I don't think the al Houthi-Saleh forces will let the city go without a good fight,” she added.

Nancy Youssef contributed reporting.