The on-going G20 Summit in Osaka, Japan, is a crucial moment for the world to uphold multilateralism and rules-based world order that are under the grave attack by US unilateral and protectionist behaviors.

European Union leaders highlighted their goals for the summit on Wednesday in a joint letter issued by European Council President Donald Tusk and European Commission President Jean-Claude Juncker. They include upholding the rules-based world order and multilateral institutions that underpin it and calling on the G20 leaders to step up action to mitigate the existential climate threat and safeguard free and fair global trade.

These are goals that leaders of China and many other countries have also been advocating, in total contrast to the United States administration which has been withdrawing from and ignoring international organizations and multilateral agreements, and resorting to unilateral and protectionist "America First" policies.

The EU leaders, however, have not been vocal enough to call out these disruptive actions largely due to an unequal relationship with the US since the end of World War II.

The EU and its member states, for example, are among the most active in pushing for implementation of the Paris climate accord. But they have not censured the US severely enough for pulling out of the 2015 Paris Agreement. Also, they did not express any shock publicly when US Vice-President Mike Pence refused to admit climate change is a threat to the US in a CNN interview on Sunday.

According to the Financial Times, which saw the draft G20 communiqué prepared by the Japanese government, the document avoids phrases such as "global warming" and "decarbonization" as an apparent capitulation to the demands of the White House.

If it were indeed the case, would the EU endorse such a watered-down version on climate change that contradicts its ambitious goals, in order to appease the US?

On Iran, the EU and its key member states, Britain, France and Germany, have remained committed to the Iran nuclear deal despite the US withdrawing from the agreement. They have tried hard to establish the Instex special purpose vehicle to help companies bypass the US sanctions on Iran. And they opposed the latest round of US sanctions on Iran announced on Monday. But the kind of forceful language needed from the EU leaders to condemn the US actions was not there.

Though the EU is still unable to fight the US financial power, it's extremely important for its leaders to speak up more often and more aggressively against US bullying. Before leaving to attend the G20 Summit, Tusk noted that the biggest risks to the global economic outlook are trade and geopolitical tensions, saying he would take this message to the G20.

What is less clear is whether he will publicly call out the US administration which has been waging an unjust tariff war against not only China but also many other economies, including the EU, not to mention an unjust war against Chinese high-tech companies such as Huawei.

In April, when the US threatened to slap tariffs on $11 billion worth of goods from the EU in response to subsidies that support Airbus, the EU quickly announced that it was considering imposing tariffs on $22 billion worth of imports from the US.

It is no secret that the EU and most of its member states are at odds with a US administration that swears by unilateralism and challenges the rules-based international system. But only when they speak up loud and clear can the EU fulfill its goals set for the G20 Summit and its aspiration to be a true global leader.

The author is chief of China Daily EU Bureau based in Brussels.