Evidently, trade protectionism is now posing a real and serious challenge for global free traders and, if left unchecked, it is very likely to retard or even reverse the current hard-won world economic upturn.

Later this week, Chinese Premier Li Keqiang is set to embark on an official visit to Europe. It presents a good chance for the two sides, both staunch supporters of global free trade, to cement cooperation and enlarge their consensus on defending the rules-based multilateral trading system.

During the week-long trip, the premier will also attend the 7th meeting of leaders from China and the Central and Eastern European Countries in Sofia, Bulgaria, and co-chair in Berlin the 5th round of China-Germany intergovernmental consultations with his German counterpart, Angela Merkel.

China and European countries are natural partners. They are even more so in a world of growing uncertainties. They firmly believe that free trade is a powerful engine for global economic growth, while unilateralism and trade protectionism could trigger volatility and recession in the global economy.

In Washington, trade hawks seem to have betrayed the current multilateral trading order it used to defend, and are instigating protectionism by playing with tactics of tariffs.

In just several months' time, the Trump administration has fired a fusillade of tariff warning shots. It has decided to slap steep tariffs on steel and aluminum imports from many of its European Union allies and threatened to levy punitive tariffs on tens of billions of dollars worth of Chinese imports.

In the face of these challenges, European nations and China have refused to sit still. Their responses so far are as reasonable as they are legitimate.

While sparkplugging the very spirit of free trade, they should also jointly work to reform existing global economic governing institutions so that they can be more open, inclusive and resilient.

Also, they should call on all members of the international community to resist the temptation of resorting to unilateral actions in fixing trade disputes, and to stay committed to talks within the framework of the World Trade Organization, the backbone of today's multilateral trading system.

Over the past 40 years since China adopted the reform and opening-up policy, it has done its fair share of promoting economic openness and free trade, and has made great contributions to the world. It has promised to do more.

Only days ahead of Li's visit, China introduced huge new tariff cuts covering consumer goods and automobiles to help increase imports.

That is part of Beijing's proposed measures made at Boao Forum for Asia in April to pursue further opening up, including significantly increasing market access, creating a more attractive investment environment, strengthening protection of intellectual property rights and expanding imports.

Germany is home to many of the world's car manufacturing giants. For these businesses, China's latest moves mean more direct market opportunities.

As China further opens its doors as it has promised, China and European countries can further tap their great potential for cooperation in areas including high-tech, innovation, agriculture, finance, digital economy, e-commerce and climate change.

In the final analysis, it is their joint responsibility to use their fruitful and mutually-beneficial cooperation to prove to the rest of the world that free and open trade is the only sure way towards fair benefits for all.

After all, closing doors and indulging in protectionism would produce losers uniformly. The only difference is who loses more.