As a Navy SEAL, Megan Hernandez had completed many critical and dangerous missions. Although she is now a former SEAL, the Secretary of the Navy had contacted her to complete some crucial tasks that included rescuing kidnapped children and then helping to eradicate the threat of Somali pirates.
Those situations handled, she was now being tasked with the greatest and most important mission of her career. A country was being invaded at the whim of its most dangerous neighbor. The cold war had ended years ago and no world event had brought us closer to World War 3 than this disgusting abuse of power. Ukraine was being invaded and although they are fighting bravely, the USA simply can not allow the bear to continue its onslaught.
Megan and two of her former teammates are going to remedy this situation and hopefully get out alive. There could be absolutely no evidence or indication that the USA was behind this and she had no idea exactly who within her own government knew of this plan. That did not matter to them because SECNAV needed them and so did the world.