Frank was a soldier. He was in the field now and all his training told him how to respond to any given situation. A lull in activity was just the calm before the storm. They couldn't afford to stop being on alert. So, he came up with a schedule for the two of them. Currently he was on gun while Clint was sleeping. He kept up a regimented view of the entire area walking from area to area.
Then he saw something happening. A big purple alien looking creature stepped through an odd patch of air. Then he saw other strange beings coming in as well.
He moved his leg far enough to kick the sleeping Clint. "Look alive, Barton, we've got incoming," he said. "Looks like Hieronymus Bosch's version of Barney and his pals."
While he waited for Barton to get around Frank issued the alert through the coms along with the position of the intruders. Ending the message with an 'over and out'. He took his eye off the scope long enough to fill a cup with room temperature coffee.
@hereshawkguy