Americans who remember the fall of South Vietnam in 1975 – and the frantic evacuation of U.S. troops and civilians from Saigon – may be watching events in Iraq with a dismayed sense of deja vu.

Insurgents including al-Qaida elements are on a steady march through Iraq, with the goal of toppling the U.S.-backed government. Already, cities including Fallujah and Mosul have been taken by the revolutionaries.

Nearly 4,500 Americans died in Iraq from the invasion in 2003 through the alleged pullout of U.S. troops in 2011. More than $1 trillion was spent in an attempt to build a friendly, democratic system in that country. Now it seems as if all of that may have been for naught.

And the conflict is not over. Already U.S. aircraft have been used to supply arms and ammunition to Iraqi government forces. At some point, Americans may come under fire.

Should the insurgents capture Baghdad, a virtual repeat of Saigon may ensue as al-Qaida elements attack Americans. The U.S. embassy complex in Baghdad alone houses about 5,500 U.S. troops and civilians.

President Barack Obama’s handling of crises abroad does not inspire confidence. Members of Congress should demand to know what the plan is to protect Americans caught in the Iraqi war.