A leaked email written by the UN's envoy for Yemen has cast new light on negotiations to end the country's brutal war, and raises questions about the growing presence of al Qaeda, as well as the dedication to UN-brokered talks by Saudi Arabia, whose multinational coalition has bombed Houthi rebels and their allies since late March.

The email was sent by special envoy Ismail Ould Cheikh Ahmed to Jeffrey Feltman, the UN's undersecretary for political affairs and a former US State Department official. In it, the envoy confirms that Houthi rebels and the party of former president and Houthi ally Ali Abdullah Saleh have expressed willingness to accept — with some reservations — a UN Security Council resolution, approved in April. This demanded the rebels "withdraw their forces from all areas they have seized, including the capital, Sanaa." VICE News first reported communications of this nature between Houthi representatives and the UN last month.

Accompanying the email was a document outlining steps to solve the crisis in the country, including a permanent ceasefire, a monitoring mechanism, and the forming of a government of national unity.

"AA/GPC agreed to a new wording on UNSC resolution 2216 that states unequivocally that they are committed to the implementation of 2216 (see document attached) with the exception of article which infringe on Yemeni sovereignty and those related to sanctions," wrote Ould Cheikh Ahmed, referring to Ansar Allah (AA) — another name for the Houthis — and Saleh's General People's Congress party (GPC).

"In addition, the new text includes acceptance of the return of the current government for a period of 60 days during which a government of national unity shall be formed," wrote the envoy in the email, which was obtained by VICE News. According to Ould Cheikh Ahmed, during talks, the Houthis gave ground on certain language, including "mandatory support by the international community for reconstruction that was in the earlier version."

"The latter was particularly opposed by KSA [Kingdom of Saudi Arabia] and GCC [Gulf Cooperation Council] who did not want it to be interpreted as a form of mandatory compensation," added the UN envoy. In April, Saudi Arabia promised the UN $274 million in emergency funding for Yemen. Last week, after several months of contentious negotiations that angered many UN officials, the Saudis agreed to transfer $53.5 million of the total to aid agencies.

Late on Monday, the UN issued a statement, saying it was "disturbed by press reports regarding the leak of internal United Nations correspondences." While it contended that portrayals of the email in the Yemeni press "do not reflect the position of the Special Envoy," the UN did not question the authenticity of the email itself. Several diplomatic and UN sources confirmed to VICE News that the communication had been sent by Ould Cheikh Ahmed.

Yemen's president, Abd Rabbuh Mansour Hadi, fled the country in March, as the Houthis capitalized on gains and expanded southward. Hadi, along with most of Yemen's official government, has since been ensconced in Riyadh, Saudi Arabia, where they have offered support for the Saudi-led coalition's efforts to repel the Houthis and their allies.

Saudi Arabia and their allies accuse Iran of supporting the Houthis, who hail from a Shia minority in Yemen's north. Hadi and the coalition say they will not accept anything short of the Houthis laying down their weapons and withdrawing from all areas they have seized since last year.

The leaked note refers to a series of meetings the special envoy undertook in Muscat, the capital of Oman, with the Houthis, as well as representatives from Houthis, the US, UK and Oman, and "KSA intelligence officers." Hadi's government has downplayed the significance of the talks in Muscat.

"The discussions focused on possible confidence building measures such as a pullback from border areas in exchanges for a cessation of airstrikes and agreements in which they would cease operations within Saudi Arabia," Ould Cheikh Ahmed said of the Houthis. "This was the first time that Ansar Allah have been open to discuss limited and geographically specific agreement. Although they repeated that the return of President Hadi would be unacceptable, they expressed their openness to the return of the government for a limited time."

Watch the VICE News documentary, **Seeking Refuge in Djibouti: Escape From Yemen:**

The leak of the email comes at a time of intensified military activity by coalition members — and losses among its troops, who have increased their presence in the country. On Friday, 45 Emirati soldiers, along with 10 soldiers from Saudi Arabia and five from Bahrain, were killed when Houthi forces hit an ammunitions depot in Marib province. The attack was the deadliest suffered by the coalition; shortly afterwards, residents of the Houthi-controlled capital Sanaa reported heightened and deadly airstrikes.

"We will press ahead until we purge Yemen of the scum," said Abu Dhabi Crown Prince Sheikh Mohammed bin Zayed, after the missile attack.

Though the Houthis and their allies have been pushed out of large swaths of the country's south, most notably the port city of Aden, Ould Cheikh Ahmed noted that those who repulsed the Shia rebels were in many cases only allies of convenience with the coalition.

"The instability and violence which have plagued Aden following its capture is likely also a source of concern," wrote the envoy. "The mostly pro-independence Hiraak fighters are unwilling to cooperate fully with the GoY [Government of Yemen] in attempts to expand northward."

"This leaves the coalition dependent on ground troops from Islah, Salafi and AQAP related groups," he wrote, referring in the later instance to groups tied to al Qaeda's affiliate in Yemen, or the terror outfit itself. The envoy said al Qaeda's "increased visibility" in Aden after the Houthis left "has started to raise serious concerns for UAE and in some KSA circles."

On Monday, Doha-owned al Jazeera reported that 1,000 of Qatar's soldiers would be deployed in Yemen's Marib province, along with 200 armored vehicles and 30 Apache helicopters. Al Jazeera said that more troops were expected to deploy "with the aim of securing the Jawf governorate."

Several thousand Emirati soldiers are already believed to be in Yemen, along with Saudi forces.

More than 4,500 people — roughly half of them civilians — have been killed by all sides since the start of the coalition's intervention on March 26, according to the UN. Both the Houthis and the coalition have been accused of gross human rights violations and war crimes. The Houthis regularly shell residential areas indiscriminately, most recently in the contested city of Taiz. As they retreat, anti-Hadi forces have been documented leaving thousands of deadly anti-personnel mines in their wake.

The coalition, meanwhile, has been cited repeatedly by international human rights groups and the UN for likely violating international law by bombing civilian areas. Groups including Human Rights Watch have raised questions over US support for the coalition. Washington provides logistical and targeting assistance to the Saudis, and has recently greenlit billions in arms sales for the Kingdom.

Though members of Hadi's government have called a battle for Sanaa "imminent," Ould Cheikh Ahmed, considering recent Houthi counterattacks, offered a more sobering assessment.

"The coalition's difficulties moving northward suggest that an assault on Sanaa would likely be difficult and [more] time-consuming than they had previously expected," he told Feltman.

"In light of the above, I have reached the conclusion that we should now move towards a new round of direct talks," he said. The envoy suggested that the talks, which would follow failed negotiations in Geneva in July, take place in Oman prior to the Muslim holiday of Eid al-Adha, on September 23.

But despite UN efforts and messaging from the Houthis, both sides have hardened their stance, at least on the battlefield. Past humanitarian pauses have been completely ignored by the coalition and the Houthis.

In Muscat, the envoy said he had scraped the barrel with Houthi representatives, as he pushed them to compromise.

"It will be difficult, at this stage, to push them towards further concessions," he wrote.

But whatever the Houthis tell Ould Cheikh Ahmed matters little if the Saudis don't take UN-sponsored talks in Oman seriously, something the envoy alluded to in his email.

"US officials were disappointed that Saudis had sent relatively junior representatives," wrote Ould Cheikh Ahmed, adding that "the meetings unfortunately shed very little light on KSA's strategy in the conflict or their willingness to support a negotiated settlement in the near future."