Complex sentence: Australia pledged support for UNTAG at the inception of the UN plan for Namibia in Resolution 435 in September 1978, and also made an important contribution to UN deliberations about Namibia while part of the UN Security Council in 1985--86.
Split into simpler sentences: Australia pledged support for UNTAG at the inception of the UN plan for Namibia in Resolution 435 in September 1978. Australia also made an important contribution to UN deliberations about Namibia while part of the UN Security Council in 1985--86.