(Reuters) — Foreign ministers and heads of state of the 10-member Association of Southeast Asian Nations (ASEAN) are facing a test of unity at their summit this weekend as some members express alarm over China’s growing assertiveness in the disputed South China Sea and push for a strong joint statement. Tensions ratcheted up in the past week after China positioned a huge oil rig in an area also claimed by Vietnam, with each country accusing the other of ramming its ships in the […]