Australia, one of the most China-dependent economies outside the developing world, is beginning to curb investment from the Asia-Pacific titan. China accounts for 30 percent of Australia's trade, in addition to investing in key sectors. But this reliance has long caused ripples of controversy, because it touches on the deeper fears of isolation and of foreign control arising from Australia's geopolitical position. Amid a roiling controversy over Chinese influence over Australian politicians and parties, the country unveiled tighter restrictions on investments, citing national security concerns while turning an eye toward China....