Four British Army veterans, known as the "Xenon Climbers," became the first to summit Mount Everest on Wednesday with the help of xenon gas therapy, according to Anadolu Agency.

The team, including Alastair Carns, parliament member and minister for veterans and people at the Defense Ministry, along with Garth Miller, Anthony Stazicker and Kev Godlington, began their mission last week to summit Everest and return to London within seven days.

They want to accelerate acclimatization by using xenon gas to boost red blood cell production.

Austrian mountaineer Lukas Furtenbach, who leads the expedition through his company, Lukas Adventures, wrote on Instagram: “Mission Everest 7days team on the the summit!! Safe descent.”

Unlike traditional methods involving lower peaks or multiple rotations, the team from the UK flew directly to Kathmandu, took a helicopter to Everest Base Camp, and immediately began their ascent.

The team completed more than 500 hours of hypoxic training, including sleeping in a hypoxic tent and training with a mask.

Special regulators on the mountain were used to enhance their oxygen intake. They also used a controversial technique, breathing xenon gas before their ascent, ExplorersWeb reported.

Miller, a two-time Everest summiteer, said the team underwent 30-minute xenon therapy at a hospital in Germany. He noted that xenon’s neuroprotective properties reduce the risk of Acute Mountain Sickness (AMS), allowing the team to ascend faster without the dangers of AMS, despite not speeding up the climb.

The use of xenon gas has sparked debate among the mountaineering community. The International Climbing and Mountaineering Federation (UIAA) has expressed concern, citing a lack of evidence about its efficacy at high altitude, as well as potential health risks such as brain and respiratory problems.

Team defends the use of technology, however, stating that as busy professionals with families, a traditional seven-to-eight-week Everest expedition is not feasible.

Furtenbach also claimed that xenon is simply another tool for a safe, fast ascent, like specialized gear or oxygen.