Complex sentence: He tries to convince the President to shut down the G.I. Joe team, and when this fails, sends a team of covert Cobra operatives, named the Phoenix Guard, to infiltrate "The Rock" and kill the G.I. Joes.
Split into simpler sentences: He tries to convince the President to shut down the G.I. Joe team. When he fails, he sends a team of covert Cobra operatives called the Phoenix Guard to infiltrate "The Rock" and kill the G.I. Joes.