The announcement of the president of the United States was accidentally released in the middle of the radio broadcast. The president declared that the country was in a state of emergency and suspected the enemy missile invasion.

In the middle of it is an adverbial and a prepositional phrase for the approach of a suspicious enemy, which is used as an attribute to modify an emergency. Suspected indicates suspicion and awareness, Suspected indicates suspicion, and approximate is the compound object of the present participle as a preposition.