Met with le duc tho, a north vietnamese negotiator, in an effort to end the vietnam war peacefully.

The answer was Henry Kissinger.  At point, the war was already dragging and public opinion now turned against the war. So Kissinger arranged for negotiations to withdraw from Vietnam.  With the withdrawal of U.S. troops, the North conquered the South and Vietnam was united under communist rule.

i think its the outcome of people's preferences.

alaska is the answer to this