Malaysia established diplomatic ties with North Vietnam on 31 March 1973 at the ambassadorial level after the Paris Peace Accords were signed that year. An agreement between the ambassadors of Malaysia and Vietnam was reached in 1975. The following year, Malaysia first opened its embassy in Hanoi, while Vietnam also opened its embassy in Kuala Lumpur on 29 May 1976. In the mid to late 1970s, bilateral ties were strained as Malaysia pressured Vietnam to embrace the ZOPFAN concept, which the latter interpreted as a version of the anti-communist containment policy. During a bilateral summit in August 1977, Malaysia's Prime Minister Hussein Onn made promises to provide economic and technical assistance to rebuild Vietnam's war-torn economy. When Vietnam invaded Cambodia in 1979, many Vietnamese sought refuge in Malaysia from that time onwards and into the 1980s, and caused economic and national security problems to Malaysia especially to its racial balance as most of the Vietnamese refugees resemble the Chinese people. Bilateral ties normalised from 1988 onwards, when Vietnam announced plans to withdraw from Cambodia. In the early 1990s, government leaders of both countries held several diplomatic visits and summits, which produced many agreements that emphasised economic co-operation and development. Strengthening ties also saw the opening of a consulate office in Ho Chi Minh City in January 1991. Vietnam expressed its interest in joining ASEAN with Malaysia's support in 1994 as the countries continued to foster close economic ties. Vietnam joined ASEAN in 1995; its entry was warmly welcomed by Malaysia.