another town fell on Sunday. And security is beefed up, and U.S. Staffers evacuated after a string of bombings in Baghdad this weekend. And Martha Raddatz is in Baghdad. All sides mobilized for battle... See More
another town fell on Sunday. And security is beefed up, and U.S. Staffers evacuated after a string of bombings in Baghdad this weekend. And Martha Raddatz is in Baghdad. All sides mobilized for battle there. Reporter: They certainly are, George. Those 100 U.S. Marines have now arrived here in Baghdad to guard the U.S. Embassy. And we witnessed an incredible sight this morning. Young Iraqi men lining up to defend Baghdad. They came by the thousands. Young shia men from all around Baghdad, some barely in their teens, volunteering to fight jihadists that have taken a swath of Iraq. A marching band was there for the send-off. There seems to be an incredible deal among these young men, they seem absolutely fearless. They have no idea what they're getting into. These graphic images of mass executions of american-trained Iraqi soldiers were released by the jihadist group, Isis, the islamic state of Iraq and Syria. They are threatening strict, islamic law, killing thousands who stand in the way. But Iraqi forces have been striking back. Helicopters launching powerful rockets at targets near the main road leading to Baghdad. And here in Baghdad, a string of explosions blasted the city, killing as many as 15. Those attacks and the threat of a massive Isis attack on Baghdad has prompted the U.S. Embassy to evacuate a significant number of employees and bring in close to 100 specially-trained Marines and 50 additional security personnel rushed to the embassy in Baghdad. The U.S. Has also moved three warships into the persian gulf, with president Obama considering air strikes. The Obama administration is considering talks with Iran to help with political reconciliation here in Iraq. But top republicans say action is needed now. If Baghdad falls, if the central government falls, a disaster awaits us of monumental proportions. Reporter: The embassy here is still open, but clearly they are fearing the worst. George and robin. Thanks. Now to Amy with the other top stories.
This transcript has been automatically generated and may not be 100% accurate.