BEIJING: China sending an oil rig to waters disputed with Vietnam is a move to assert its legal claim and practical hold over contested territory whatever the short-term political and diplomatic costs, analysts say -- but could play into Washington’s hands.

Beijing’s controversial move to dispatch the deep-water rig along with a reported 70 vessels triggered clashes in the West Philippine Sea (South China Sea), just after a visit to the region by US President Barack Obama and ahead of this weekend’s Association of Southeast Asian Nations (ASEAN) summit.