forces are scheduled to be out of iraqi by the end of the month, but a violent attack earlier this week in the heart of baghdad is raising questions about whether iraqi forces will be up to the job of maintaining security. our jim axelrod is in baghdad tonight. jim, good evening. let me ask you, first of all, obviously, this car bomb earlier this week a cause of great concern. even more so now that iraq's prime minister maliki believes it was an attempt to his life. what can you tell bus that? >> reporter: russ, this is actually the third version of an explanation for the car bomb. frankly, we don't know which, if any to believe. but whatever the reason, the car bomb is especially alarming because of where it happened. the green zone, that four-square-mile area where the u.s. embassy is located. for years it's been thought of as the safest part of the city. the fact that somebody could actually get a car bomb inside the green zone and detonate it cast doubt on the ability of the iraqi security forces to keep the peace here. but if it was, indeed, an attempt too maliki's life, that just raises the stakes.