So the bloc announced a plan that is meant to retaliate in nearly equal measure.

The response will come in two parts. The bloc had increased tariffs on a range of goods in retaliation to U.S. measures during Mr. Trump’s first term, but they were suspended under the Biden administration. That suspension will be allowed to lapse on April 1, increasing tariffs on $4.5 billions of euros worth of products that include boats, bourbon and motorcycles.

The bloc’s second step, it said, would be to place tariffs on about €18 billion worth of additional products. Representatives from countries across Europe will consult for two weeks before officials finalize the list of affected products.

Items that have been proposed for inclusion are industrial and agricultural. They are meant to target products — including soybeans, beef and chicken — that are important exports from Republican strongholds. Those include the Louisiana district that elected Mike Johnson, the House speaker.

The goal is to have the new measures in force by mid-April.

The announcement was Europe’s opening move in an unfolding trade conflict — one that is widely expected to intensify over the month ahead.

For the bloc, the American steel and aluminum tariffs are just the start of what Mr. Trump has threatened. He has repeatedly vowed to set wide-ranging tariffs on American trading partners globally as soon as April 2. He has suggested that levies on cars in particular could be 25 percent, a figure that would be painful for German and Italian automakers.

“We’re now in this escalating spiral,” said Carsten Brzeski, the global head of macro research at the bank ING.

On the one hand, the European Union does not want to escalate the trade war. European officials have called tariffs “economically counterproductive,” warning that a tit-for-tat tariff fight would harm everyone involved.

“Tariffs are taxes,” Ursula von der Leyen, the president of the European Commission, the bloc’s executive arm, said in a televised statement on Wednesday. “Jobs are at stake, prices up, nobody needs that.”

But the Trump administration has been reluctant to negotiate, which is pushing European policymakers to adopt a more aggressive stance.

“I traveled to the U.S. last month; I was seeking constructive dialogue to avoid the unnecessary pain of measures and countermeasures,” Maros Sefcovic, the European Commission’s top trade official, said during a news briefing this week. “In the end, as it is said, one hand cannot clap. The U.S. administration does not seem to be engaging to make a deal.”

E.U. leaders emphasized on Wednesday that the bloc’s response is intended to be proportionate, and Mr. Sefcovic stressed that they were avoidable “if the U.S. administration accepts our extended hand.”

Mr. Trump’s tariffs come at a tough moment for the European economy. After several years of flagging growth, businesses across the bloc are staring down the prospect of worsening trade conditions that could hurt their overseas business.

Groups representing the German steel industry, for instance, have said that the tariffs come at an “inopportune time,” when producers in the European Union are dealing with cheap competition from China.

Europe has not been caught by surprise, at least. A trade-focused group within the European Union, colloquially called the “Trump task force,” spent much of last year preparing for various trade conflict scenarios.

But it has been hard for Europeans — and other American trading partners — to decide how to respond. It is also not clear what Mr. Trump’s goals are or which ones will ultimately be retained, because his administration has made a habit of threatening and then backtracking, at least temporarily.

“It’s hard to know what is going to stick and what’s not going to stick,” said Michael Strain, the director of economic policy studies at the American Enterprise Institute in Washington, which recently hosted an event with Mr. Sefcovic.

European officials have also struggled to get their American counterparts on the phone. Ms. von der Leyen has not spoken individually with Mr. Trump since his inauguration.

Asked at a news conference on Sunday when she might speak to him, she said: “We will have a personal meeting when the time is right.”

Kaja Kallas, the bloc’s chief diplomat, was supposed to meet with Marco Rubio, the American secretary of state, in Washington in late February, but Mr. Rubio canceled that meeting.

And diplomats from across the European Union and its member countries have struggled to identify whom to talk to in the Trump administration, in part from a lack of clarity about how decisions are being made.

“I do think there’s a level of consternation at the objectives of the administration,” said Jörn Fleck, senior director with the Europe Center at the Atlantic Council, a Washington-based research institution.

He said that Europe might struggle more to respond in a world in which the United States does not want to simply make a deal, but rather wants to fundamentally reorder the global trade order so that more is produced in the United States.

“Maybe there isn’t any deal to be had,” he said.