U.S. President Barack Obama has pledged that Washington will remain a strong partner for Iraq as American troops exit by year-end. He also played-down the risk that the departure of American forces creates a power vacuum Iran can exploit. The withdrawal of almost all US troops from Iraq by December 31st has created uncertainty at a time the region remains roiled by the Arab Spring, and amid fear Syrian instability could spread sectarian strife into neighboring Iraq. But President Obama told a press conference with Iraqi President Nuri al-Maliki that the US remains a strong Middle East presence. And Maliki pledged his commitment to continue building ties with the US. Obama also said the US government had requested the return of a spy drone downed over Iran but declined to discuss if its loss could compromise US national security. Obama and Maliki later visited Arlington National Cemetery and jointly laid a wreath on the Tomb of the Unknowns as the US and Iraqi national anthems were played.