The U.S. Embassy in Yemen was attacked Sept. 17. Preliminary reports suggest that there was an initial suicide car bomb explosion followed by 15 minutes of heavy gunfire (with the possibility that rockets or mortars were used) after which there were two additional explosions. According to the reports, the attackers came in two separate vehicles and there are a number of casualties. The explosions and gunfire suggest that suicide bombers as well as gunmen were involved in what appears to have been a complex attack likely perpetrated by jihadists affiliated with the Yemeni node of al Qaeda. That said, it is unlikely that the attackers were able to breach the outer perimeter of the compound, given that U.S. embassies in the region are heavily barricaded. Therefore, those killed or wounded are likely locals, particularly security personnel at the gate of the facility. Yemen, whose intelligence and security services are filled with Salafist-jihadist elements, has been the scene of a recent uptick in Islamist militant activity. This has prevented Sanaa from cracking down on jihadists operating in the country, which has become a major sore point between the government of President Ali Abdallah Saleh and Washington. The attack on the U.S. Embassy will only further aggravate the situation, which in turn could lead to greater instability in the country. Washington will likely increase the pressure on Yemen, and Sanaa will take some reactive security measures. But there is little that Saleh can do without risking a domestic backlash.