Nations often change their minds. But over Vietnam the changes have been little short of, well, mind boggling. Just 50 years ago the United States and Australia saw Hanoi as the puppet of an aggression-minded Beijing. Intervention against Hanoi in the Vietnam civil was seen as crucial in preventing the advance of China and communism southwards into the rest of Asia — the domino theory. Today both the U.S. and Canberra have switched 180 degrees. Both seek a close relationship with Hanoi in the hope that Vietnam will help block yet another feared southward Chinese advance, this time into the South China Sea.

Where once the U.S. rained bombs, napalm and toxic Agent Orange over Vietnam, it now bombards Hanoi with invitations for its highest officials to visit the U.S. On his recent visit to Washington, the general secretary of the Vietnam communist party, Nguyen Phu Trong, was granted the privilege of a cosy tete-a-tete with President Barack Obama in the White House Oval Office. Even close allies do not get that sort of treatment.

True, nations are allowed to change policies as circumstances change. But the Hanoi then was the same as the Hanoi of today — sensible, pragmatic and fairly anti-China. When pro-communist President Ho Chi Minh in 1945 announced Vietnam's breaking free from French domination he quoted from the U.S. Declaration of Independence. Yet somehow our policymakers managed to convince themselves despite all the evidence to the contrary that Hanoi was dominated by a communist ogre in Beijing that had to be contained at all costs.