China should face “a higher cost” for supporting Russia in the war against Ukraine, the EU’s incoming foreign policy chief, Kaja Kallas, has said.

The former Estonian prime minister was speaking to MEPs during a three-hour hearing before she takes office, when she listed Ukraine’s victory as a priority – stronger words than vaguer formulas of support voiced by some EU politicians.

“Victory of Ukraine is a priority for us all; the situation on the battlefield is very difficult,” Kallas told MEPs in her opening remarks. “That is why we must keep on working every day, today, tomorrow and for as long as it takes, and with as much military, financial and humanitarian aid as needed.”

In a carefully worded overture to the incoming Donald Trump administration, she said support for Ukraine was in the US’s interest. “If the US is worried about China, or other actors, then they should also be worried about how we respond … [to] Russia’s war against Ukraine, because we see how Iran, North Korea, China – more covertly – and Russia are working together.”

Later asked about Trump’s intentions, she said: “I don’t think anybody really knows what the new president-elect is doing” and said the EU needed “first and foremost” to get information from the US on its plans, adding: “Isolation has never worked for America.”

On defence, the EU needed “a drastic change of mindset”, she said, adding that the west “cannot accept” that Russia, Iran and North Korea produce more ammunition than the whole Euro-Atlantic community.

As Estonia’s prime minister, Kallas was one of the originators of an EU plan to provide Ukraine with 1m rounds of shells, but progress has been slow.

She also said the EU would “strengthen our mutual security by working more closely with the United Kingdom”, the sole reference to the UK in the three-hour session.

Asked about how Europe should respond to authoritarian states supporting Russia, she said the EU needed to signal to China that its aid to Moscow had “consequences” and “a higher cost” but did not offer specifics.

She wanted to discuss Iran with EU foreign ministers, she said, but twice failed to answer a question about whether she supported designating Iran’s Revolutionary Guards (IRGC) a terrorist organisation, a subject that has long divided member states.

Along with the war in Ukraine, she described the situation in the Middle East as an “urgent” priority. She expressed support for a two-state solution and described attacks on civilians and civilian infrastructure as “heartbreaking”, while side-stepping attempts by MEPs to get her to condemn Israel’s government.

Kallas, a lawyer and MEP before she became Estonia’s first female prime minister in 2021, is one of six European Commission candidates appearing before the parliament on what has been called “super Tuesday”. Unlike the 25 other nominees to join Ursula von der Leyen’s second commission, which is expected to take office on 1 December, Kallas has already been confirmed as the EU’s high representative for foreign policy, a position appointed by EU governments.

But in order to also become a vice-president of the commission, she needs approval from MEPs.

These two roles – her position is known as double-hatted in EU jargon – point to the challenges of the job: touring the globe as the EU’s chief diplomat, while coordinating foreign policy between 27 national capitals that have frequently diverging views, and leading the EU’s cash-strapped foreign service from Brussels.

In her opening remarks to MEPs, Kallas referred briefly to her childhood growing up behind the iron curtain in what was the Soviet Union.

During the Soviet deportation of 1941, Kallas’s mother was deported to Siberia as a six-month-old baby with her mother and grandmother. They were not allowed to return to Estonia until a decade later. Her mother went on to marry Siim Kallas, a central bank chief, who played a critical role in Estonia’s post-Soviet transition, serving as Estonia’s prime minister from 2002-03 and 10 years as a European commissioner until 2014.

Kallas, 47, suggested her experience as an Estonian could help her turn a fresh page with African governments, which have seen previous EU high representatives from former colonial powers, including Spain, Italy and the UK.

Discussing the EU’s future cooperation with Africa, Kallas said she was in “a very good position” coming from a country that experienced “what it means to fight for its freedom”. She promised “a partnership of equals” with African states, as well as cooperation to manage migration. But she faced no specific questions about the EU’s controversial migration deals with Tunisia or Egypt, or the €5bn trust fund for Africa, which aims to deter migration and was recently given an excoriating review by the EU’s auditors.

She said the EU had to strengthen Europe’s defence industry, but warned against duplicating Nato’s military role, saying: “If we have two parallel structures the ball might fall between those chairs and we don’t need that.”

Kallas faced several questions on Ukraine from far-right MEPs, who were elected in greater numbers than ever before in June’s elections. Responding to a question about whether Trump would “put an end to the fantasies” that Ukraine would win, she said that agreements that brought only a short-term peace would bring only more wars, citing the 2015 Minsk agreement after Russia’s annexation of Crimea and aid to pro-Kremlin separatists in the Donbas. Kallas cited the Yale historian Timothy Snyder, who argues that Russia must lose decisively to become “a ‘normal’ European country”.

Kallas continued: “Russia has never lost its last colonial war. We have to do everything that they will lose it now.”