In light of the decline experienced by the Soviet Union and the socialist countries of Eastern Europe, the Vietnamese Government began repairing diplomatic relations with neighbouring countries as part of a greater effort to rejuvenate Vietnam's shattered economy. Since its invasion in 1979, China had placed sustained pressure on the northern borders of Vietnam, with the province of Ha Tuyen regularly shelled by Chinese artillery. In September 1985, Chinese bombardment of Ha Tuyen reached a peak when 2,000 rounds were fired. To reduce the state of hostility along the border region, and ultimately normalise relations with China, the Vietnamese Government dropped all hostile references to China at the 6th National Party Congress in December 1986, and also adopted the Đổi Mới policy. In August 1990, as the Cambodian Peace Plan, authored by Australian Foreign Minister Gareth Evans, was being endorsed by the UN Security Council, both China and Vietnam moved towards accommodation.