BRUSSELS, June 8 (Xinhua) -- The European Union (EU), who has counted itself as the America's closest partner, has been infuriated and alarmed by U.S. President Donald Trump's decision to pursue protectionist measures.

Amid waves of criticisms, the United States last week decided to impose tariffs of 25 percent on steel and 10 percent on aluminium, for the EU, Canada and Mexico, and those new tariffs took effect from June 1. The imposition of the new tariffs has been viewed as "pure protectionism" by the EU.

DARK SHADOW OVER G7

The steel and aluminum tariffs imposed by the Unite States on its trading partners cast a dark shadow as the G7 leaders meet in Canada's Quecec.

"It is evident that the American president and the rest of the Group continue to disagree on trade, climate change and the Iran nuclear deal. What worries me most, however, is the fact that the rules-based international order is being challenged. Quite surprisingly, not by the usual suspects, but by its main architect and guarantor: the U.S.," European Council President Donald Tusk told a press conference before the G7 summit in Charlevoix, Canada.

During the EU-Western Balkans summit in Sofia in May, Tusk asked the EU leaders: "With friends like that, who needs enemies?" "Europe should be grateful to President Trump. Because thanks to him we have got rid of all illusions. He has made us realise that if you need a helping hand, you will find one at the end of your arm," Tusk said.

The EU has responded immediately to the U.S. steel tariffs by taking retaliatory measures, including launching legal proceedings against America in the World Trade Organization (WTO) on June 1 and setting to impose retaliatory tariffs on a list of U.S. products from early July.

"The EU believes these unilateral U.S. tariffs are unjustified and at odds with World Trade Organisation rules. This is protectionism, pure and simple," Jean-Claude Juncker, President of the European Commission, said in a statement after the U.S. announcement of levying steel and aluminium tariffs.

The British Prime Minister Theresa May said on June 1 that she was "deeply disappointed" at the "unjustified" decision by Washington to apply tariffs to EU steel and aluminium imports.

"Our steel and aluminium industries are hugely important to the UK, but they also contribute to U.S. industry including in defence projects which bolster U.S. national security," she said.

"The EU and UK should be permanently exempted from tariffs and we will continue to work together to protect and safeguard our workers and industries," May added.

G6+1

French Finance Minister Bruno Le Maire condemned the Unite States on Friday when speaking at a business conference in Berlin.

"The U.S. has decided to end the multilateral game to defend its own economic and unilateral interests through sanctions and tariffs, without taking into account Germany, Britain and France, its closest and oldest allies," he said.

"Our European future is at stake. We must act, it is now or never," the minister said.

He said France did not want a trade war and the EU must be able to respond to U.S. tariffs. "We do not negotiate with the pistol on the chest," Le Maire added.

He has recently described the G7 summit, at which trade issue would be discussed by the leaders of seven of the largest developed economies in the world, as "more of a G6+1, with the U.S. alone against everyone".

U.S. "CROSSING RED LINE"

"The U.S., by citing bogus security concerns to defend tariffs on steel and possibly also on cars, is crossing a red line," Gabriel Felbermayr, director of the Ifo Center for International Economics told Xinhua.

"The WTO is crucial, because it binds members' trade policy, therefore eliminates uncertainty about tariff levels. It also provides a forum to deal with trade conflicts. In both the functions, it has been very successful," he said.

Felbermayr said the other WTO members should stand shoulder to shoulder to defend the WTO.

Siemens CEO Joe Kaeser also sharply criticized Trump's trade policies at a business meeting in Beijing on Wednesday.

"The right answer to lack of competitiveness is innovation and productivity and not tariffs and tweets," Kaeser told a gathering of business representatives, according to DPA reports.

"We live in a time where long-standing agreements and alliances are being challenged," he added.