Dale seemed to be okay when he returned from duty in Afghanistan in June 2009, despite witnessing his two best friends being killed when their tank exploded. Six months after his return, though, he began having nightmares and flashbacks about his experiences and became constantly vigilant. He would jump at even the slightest noise. Finally, his wife insisted that Dale see a therapist. The most likely diagnosis is .

Post traumatic stress disorder

Explanation:

Post traumatic stress disorder is a disorder that occured to someone when that person is unable to recover from a dangerous or scary event that has happen to him or her in the past.

It can also means inability of a person to recover after witnessing an event that is terrified . This type of disorder can often last for months or years because the person will always have a flash back of the events.

As in the case of Dele because he has experience a shocking and scary event in the past which make him to always have nightmares and flashbacks about his experiences making him to always jump at even the slightest noise indicate that Dele is suffered from POST TRAUMATIC STRESS DISORDER.