Reagan took on the myth of US defeat in the Tet offensive and put the blame on Robert Kennedy

Washington Examiner Op-ed:

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At the Royal Hawaiian Hotel on May 11, 1968, Reagan delivered "The History and Significance of the U.S. Role in the Pacific." Reagan laid the blame for America’s foreign policy ills — and especially for Tet — squarely at the foot of Robert F. Kennedy. Reagan began by lashing out at critics of the Vietnam War and specifically asked how the recent Tet offensive, which the U.S. and South Vietnam decisively had won militarily, could have been turned into such a loss at home? Reagan reviewed that media commentators had created the false impressions that we had lost. Reagan corrected the record:

"It was the communist attackers who took the staggering losses..and who broke at the end and pulled back. Why did this message never get through to us? Why here at home have we suffered a smashing, catastrophic, psychological defeat? A defeat we imposed on ourselves. Why, with all the power and wealth and human resources at America's command have we not been able to end this war on reasonable and honorable terms?"

Reagan then switched from attacking the liberal media and answered his own questions by zeroing in on RFK. Reagan did this by using earlier quotes from JFK and RFK and by asking when and why had RFK changed and why had he failed on his and his brother's earlier commitments to South Vietnam:

"It could be that we've listened too closely to the new isolationists. To the voices of defeat shouting down those who defend our position and our duty to be there. The most vicious attacks...come from within the party which made that intervention necessary...Nearly all these policies were developed by the late President Kennedy when these same critics were advisors close by his side. The junior senator from New York lately said that he was wrong about Vietnam in the beginning but he hasn't told us where he thinks he went wrong.
'The United States has determined that the Republic of Vietnam shall not be lost to the communists for lack of any support that the United States can render.' President Kennedy spoke those words on August 2, 1961. Does Bobby now think it was a mistake to go along with his brother's pledge? President Kennedy spoke again five weeks after that and made clear that South Vietnam should not go the way of Laos...Does Bobby now suspect it was here that his brother really went wrong?"

Then Reagan attacked RFK's own inconsistencies and contradictions:

"'We are going to remain in Vietnam and we will remain there until we win.' The person who said that in Saigon in 1962 was the closest of all to the president. Does Bobby now deplore his own judgment? For those were his words."

Reagan ended his speech by citing Kennedy’s inaugural trumpet call, to bear any burden in the pursuit of liberty, but Reagan was ashamed that Kennedy’s brother and other Democrats in 1968 “no longer hear that trumpet nor recognize its grand notes.”
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I have spent a good bit of time studying the Tet offensive and Reagan got it right and Robert Kennedy and the Democrats got it wrong.  But the Democrats got most things wrong about the war and this became their excuse for extracting themselves from a war they did not want to win.

The media got the narrative wrong on the Tet offensive.  They are making the same mistake now with the Russian collusion narrative.