Maliki got warned

Look at this sequence of events:

1. Iraq PM Maliki goes to Damascus to meet with Assad on August 18.
2. A huge bomb explodes by the Iraq Foreign Ministry in Baghdad on August 19.
3. The NYT says that the bombs are evidence that Iraq can't handle security on August 20.
4. Maliki summons the Syrian ambassador, basically accusing Syria of being behind the bombing on August 25.

It looks to me that Maliki got a warning to stay away from Syria and he obeyed or risked further attacks by people with inside access to Iraqi security. I wonder who that might be? Syria? I don't think so.