China has started drilling for oil in a part of the South China Sea also claimed by Vietnam . Vietnam says Chinese ships have made violent attacks on Vietnamese vessels . Comment: Vietnamese officials say Chinese military and civilian ships have been intimidating their vessels near the Paracel Islands -- which are controlled by Beijing but claimed by Hanoi -- since Sunday , even accusing the Chinese of repeatedly ramming into them and shooting water cannons . Situation could escalate into armed conflict , analyst says .
China has started drilling for oil in a part of the South China Sea also claimed by Vietnam . Vietnam says Chinese ships have made violent attacks on Vietnamese vessels . Comment: Situation could escalate into armed conflict , analyst says .