Operation Mountain Cobra was a UFPF joint operation between the Department of State, Federal Military, and Ranger Command (RANGECOM). It was planned during the lead-up to the constitutional ratification announcement, and officially kicked off the exact second the federation was officially binding, though logistics meant the bulk of the operation happened in the weeks following.

During the beginning of the operation, rangers were chosen to spearhead security details on a squad volunteer basis. This would provide high quality/pre-vetted troops for the understaffed Department of State, who in the rush to form a functioning department could not feasibly train their own security forces. As an added benefit rangers would have the opportunity to familiarize themselves in the strategic and diplomatic landscape the federation found themselves in.

Deployments of diplomatic missions were deplayed for a day to allow for final ranger selection interviews and initiation ceremony. The final interview was conducted personally by Reiko Eleythos and C.J. "Paladin" Bishop. Among the questions asked were:

1. Who are you, in your own words?
2. Where were you when the coup started? What did you do after that?
3. How did you come to be in the federation?
4. For whom do you fight?
5. What does victory in this war look like for you? When should the war end?
6. If the president gave you a direct order to kill USC civilians, what would you do?

Those that passed the final interview were allowed to volunteer as rangers. After an appeal from Mrs. Eleytheros rangers could participate in one of three rituals to take their oath:

• Eleytherian: An eagle feather is dipped in oak ash, then oil in silver bowl. The oil/ash mixture is sprinkled on the head individual while they recite a Ranger prayer seven times in old Agathonian. Incense is burned.
• Orthodox: Ash from a palm branch is applied to the brow of the individual in the shape of a triangle inside a square. Three verses from the Testament is read: the individual's baptismal verse, the individual's catechism verse, and a verse chosen by the chaplain.
• Secular: An oath is taken with a hand upon a copy of the constitution. The oath is a mirror to the soldier's oath, but with an added line to “Serve at the pleasure of the president for the advancement of Liberty throughout all the land.”

The diplomatic mission to the FPU was headed by Yuki Hamakura and the 19th Ranger Squad (Seraphim), 1st Ranger Corps provided security.

While traveling Seraphim Squad encountered sheriff's deputies assaulting a known bandit hideout. After assisting in securing the site a couple of Rangers attempted to loot the site, breaking the police seals.

Upon reaching the FPU border (known as the “Enclave Wall”) the diplomatic mission was aggressively searched and submitted to network scans. Otherwise unmolested, they were allowed to pass and reached the FPU capitol city of Isaipolis. There they found a lone skyscraper of the city had been designated the “Center of Administration” building, and was being used as a central spire to build a dome city around.

Upon arriving at the Center of Administration the diplomatic mission met Hera Granthos, FPU Statecraft Provost. To the federation's surprise, a diplomatic team from the USC was also in attendance, led by Lucius Cadius Titus and guarded by Scipio Polian. The FPU claimed the USC was there to be a “neutral third party observer to the proceedings.”

After an initial round of negotiations it became clear the FPU was attempting to play the USC and Federation off each other to receive better terms. After much diplomatic wrangling, it was decided that the various factions would make their best offers at a gala ball event the next day, and the FPU would come to a firm decision shortly afterwards.

At the gala 19th Squad met Nomys Prother, Chairman-Provost and head of state for the FPU. Lucius Tidus revealed to them that the USC had already organized their occupied agathonian territory as the Polus Military District, and that a selection process was underway for a system member to “ascend” and assist in the construction of a divine machine in Agathos. He was confident that after this event victory for the USC in polus would be assured, and encouraged the rangers to abandon the sinking ship while they could.

The rangers also discovered several unusual details during the course of the negotiations and gala. They found an anonymous network running which used encrypted text instead of a GUID for the name. The name decrypted to “The Future.” During the gala event, they found several (but not all) members of FPU security were concealing weapons, in addition to their standard issue batons. When confronted, one security guard produced a machine pistol and started firing into the diplomatic gathering, killing a bystander named James.

Though several party-goers were killed or injured, Seraphim Squad was able to put an end to the attack. One attacker was captured, and the others killed.

The Kingslayers reached out to Seraphim Squad through Ranger Arsenal, the corps' quartermaster. Under orders from Ranger Nocturne he convinced the squad to covertly pass a network address to FPU officials so that the Kingslayers could directly communicate with them. Not only was this was a breach of protocol, but military personnel speaking to a non-coalition faction without State Department approval could technically be considered treason.

Seraphim Squad delayed in approaching any FPU delegation members to pass over the information, but after repeated appeals by Ranger Nocturne the deed was done. The hand-off occurred around 90 minutes before the attack on the state gala.