Japan's Coast Guard plans to increase its patrols around the Senkaku Islands in the East China Sea by building 4 large patrol ships. 
The Coast Guard said it has 12 large patrol ships that can be used only for the islands. If more vessels are needed, they will be summoned from other parts of the country. But officials now said they face the need to upgrade patrols in the area now that Chinese ships have increased maritime activities since Japan's government purchased some of the islands from Japanese owners in 2012. 
The Coast Guard also plans to increase the number of personnel by 200 by the end of March, 2018, Japan's NHK World reported. 
Chinese ships have repeatedly intruded into Japan's territorial waters in recent years. 
They were spotted 36 days last year, an increase of one day from the previous year. 
Coast Guard officials said a record 15 Chinese patrol ships repeated such intrusions in August. 
They said since last fall China has increased the number of ships that are regularly spotted around the islands to 4 from 3. 
The Coast Guard said China has also tripled the number of its large patrol ships from 40 in 2012 to 120 today, and has dispatched them to the East China and South China Seas. 
Japan Coast Guard officials said while stepping up their patrol around the Senkaku Islands, they are trying not to increase tensions. 
They said they are using a channel of dialogue set up in 2015 between the Coast Guards of the two countries.

Source; QNA