The government can no longer ignore the Dire Wraith invasion as the Helicarrier of S.H.I.E.LD. comes under attack. The President of the United States addresses the nations of the globe and now the world knows the truth. And as a certain cigar chomping super-spy bluntly puts it "...now that the talkin's over...the fightin' starts!" 
The World leaders decide to getr together and leave old enmities behind to join forces against an common enemy - Dire Wraiths