Chinese companies have been keen on investing and building foreign ports in recent years. Where and why is China doing so?

This is Piraeus Port – Greece’s largest and the Mediterranean’s third largest port.

But two-thirds of its shares now belong to a Chinese company, and so does its entire operation for the next 35 years.

Piraeus is just one example of the Chinese involvement in foreign ports. Since 2009, a handful of Chinese state-owned companies, mainly led by COSCO and China Merchants Group, have extended their terminal networks to more than five dozen ports around the globe.

Particularly noticeable are those along the Maritime Silk Road. From Myanmar, Singapore, Malaysia, Sri Lanka, Pakistan in Asia, to Djibouti and Egypt in Africa, and then to Greece, Italy and Belgium in Europe, China is building gateways to these continents’ heartlands. The purpose -- to increase infrastructure links and boost trade.

Several projects in Greece's Piraeus Port, Sri Lanka's Colombo Harbor and Pakistan's Gwadar Port all had to be suspended at one time because of domestic criticism. Opponents worry that in the long run, too much Chinese control of their domestic assets will harm their countries' economy, and national security as well.

But supporters believe that Chinese investment will help bring more infrastructure development and job opportunities to the host countries.

Just two weeks ago, Pakistani officials welcomed the first large shipment of Chinese goods through its port of Gwadar. This deep-water port is a vital gateway of the China-Pakistan Economic Corridor, or CPEC, which encompasses roads and energy plans.

"Pakistan is located at the intersection of three engines of growth in Asia, South Asia, China and Central Asia. CPEC will help in integrating these regions into an economic zone offering great opportunities for people of the region as well as investors from all over the world," said Pakistani Prime Minister Nawaz Sharif. 

In return, the CPEC will shorten China's routes for oil and gas imports from Africa and the Middle East by thousands of kilometers.