The whereabouts of Malaysia Airlines Flight MH370 and the fate of the 227 passengers, including 154 Chinese, and 12 crew members aboard are still unknown.

The plane lost contact after leaving Kuala Lumpur for Beijing on Saturday. It is still too early to judge whether there was a terrorist attack as questions over two false IDs arise.

What most urgent now is to search and rescue the missing plane and people on board. Search and rescue efforts by vessels and planes from China, Malaysia, Indonesia, Vietnam, the Philippines, the United States and Singapore are still underway in the South China Sea south of Vietnam. No country can accomplish this arduous task alone given the vast area of South China Sea. However, only by sharing timely information and strengthening coordination can the seven countries better cooperate in the joint search and rescue mission.

The South China Sea encompasses an area of about 3.5 million square kilometers. About one-third of the world's shipping transits through the waters, and the airspace and aviation routes over the South China Sea are also acknowledged as one of the critical flows in the region.

Since the Declaration on the Conduct of Parties in the South China Sea in 2002, China and the members of the Association of Southeast Asian Nations have conducted joint search and rescue drills, which aims at boosting trust between China and the ASEAN countries in the less politically sensitive but very important field.

Because there are so many Chinese citizens on the missing plane, some Chinese micro bloggers have been asking why China didn't dispatch search ships and even naval vessels earlier.

Eight ships belonging to the Nanhai Rescue Burean and the Hainan Maritime Safety Administration, and an aircraft fleet were waiting for orders on Saturday and could arrive the possible crash location as early as Sunday afternoon. Two warships of the Chinese navy are on their way to join the search efforts on Sunday.

Such netizens' criticism is naive. It is sensitive for any country to dispatch its ships, not to mention navy, overseas. Especially in the South China Sea where tensions have intensified in recent years since the US began its rebalancing to Asia.

According to the 1979 International Convention on Maritime Search and Rescue, which China ratified in 1985, "Unless otherwise agreed between the States concerned, the authorities of a Party which wishes its rescue units to enter into or over the territorial sea or territory of another Party solely for the purpose of searching for the position of maritime casualties and rescuing the survivors of such casualties, shall transmit a request, giving full details of the projected mission and the need for it, to the rescue co-ordination centre of that other Party, or to such other authority as has been designated by that Party."

This explains why China couldn't dispatch naval vessels earlier despite so many Chinese citizens being on board the missing plane. However, it is truly high time China and ASEAN countries accelerated their joint maritime search and rescue cooperation. The countries and regions near the South China Sea have not yet established a well-coordinated communication mechanism because of trust deficit caused by the complicated territorial disputes in the region. Moreover, these countries differ in their maritime search and rescue capabilities, have no uniformed coordination centers, and have signed different search and rescue treaties, all of which has hindered deeper cooperation in joint search and rescue operations, which does a disservice to the people in the region.

Some other Chinese netizens kept alert to the US navy's presence in the search mission, regarding it as a symbol of US dominance in the sensitive South China Sea.