Plans for talks between the united states and china stalled when:

The talks stalled when the USA sent troops to Cambodia, in a rare turn of events, as the USA was involved in a very expensive and futile war in South Vietnam. Cambodian communist regime was involved in massive human rights abuses and oppressive practices that involved killing of millions of its people. the invasion was a pretext of disrupting North vietnam supplies.

The United States sent troops into Cambodia.

Idgaf answer yourselve u bum