In 1973 a new civilian government in Thailand created a chance for some degree of reconciliation with North Vietnam, when it proposed to remove United States military forces from Thai soil and adopt a more neutralist stance. Hanoi responded by sending a delegation to Bangkok, but talks broke down before any progress in improving relations could be made. Discussions resumed in August 1976, after Hanoi had defeated the South Vietnamese and united the country under its rule. They resulted in a call for an exchange of ambassadors and for an opening of negotiations on trade and economic co-operation, but a military coup in October 1976 ushered in a new Thai government less sympathetic to the Vietnamese communists. Contact was resumed briefly in May 1977, when Vietnam, Thailand, and Laos held a conference to discuss resuming work on the Mekong Development Project, a major cooperative effort that had been halted by the Vietnam War. Beginning in December 1978, however, the conflict in Cambodia dominated diplomatic exchanges, and seasonal Vietnamese military offensives that included incursions across the Thai border and numerous Thai casualties particularly strained the relationship.