SHANGHAI, May 21 (Xinhua) -- The ongoing joint naval drill between China and Russia means more than a boost to mutual trust and cooperation, but is also conducive to world peace, said a Chinese military researcher on Wednesday.

Chinese President Xi Jinping and his Russian counterpart Vladimir Putin attended a launch ceremony on Tuesday ahead of the week-long "Joint Sea-2014" exercise, which is being held off the Shanghai coast.

The presence of the two nations' leaders is a reflection of their resolve in responding to threats and safeguarding world peace, said Zhang Junshe, a researcher with the Naval Military Studies Research Institute of the People's Liberation Army.

Zhang noted that the exercise will focus on how to jointly protect sea lanes, which means a lot to countries and the economic security of the whole world.

Military relations between China and Russia, as seen in their fighting side by side in World War II, is "a key component of the comprehensive strategic partnership of coordination between the two countries," said Zhang, adding close cooperation in joint training, exercise, military technology, anti-terrorism has been maintained over the years.

The exercise is the third of its kind, after joint drills off the coast of Russia's Far East in July 2013 and the Yellow Sea in April 2012. The two countries have also held six joint anti-terrorism exercises since 2005.

On Wednesday, the joint exercise conducted a warfare simulation, after which commanders from the two countries discussed problems they discovered.

Though it remains to be seen how the 14 vessels, two submarines, nine fixed-wing aircraft as well as helicopters and special forces will work together in follow-up operations, some agree coordination work has become smoother.

Wang Chao, head of a coordinating team from the Chinese navy and who has participated in the previous two naval drills, said that language barriers have given way to "unified tactical thoughts".

"Now when we are planning a tactical operation, we even do not need an interpreter," said Wang.

In the following days, navies of the two countries will also join forces to simulate anchorage defense, maritime assaults, anti-submarine combats, air defense as well as identification, rescue and escort missions.