European Commission President Ursula von der Leyen and senior EU officials arrived in Kyiv on Thursday for the first EU-Ukraine summit since Russia invaded Ukraine nearly one year ago on February 24.
Speaking from Kyiv one day ahead of the summit, Ms von der Leyen framed the conflict as a "fight of democracies against authoritarian regimes".
She announced the impending launch of a centre in The Hague to document evidence of Russian war crimes during the conflict.
"The perpetrator must be held accountable," she said during a joint press statement with Ukrainian President Volodymyr Zelenskyy.
Mr Zelenskyy welcomed the delegation and urged the EU to quickly impose more sanctions on Russia.
"We see today that the pace of sanctions in Europe has slowed down a little," Mr Zelenskyy said.
"The terrorist state increases the pace of adaptation to sanctions instead. It should be resolved. We believe that we can do it together."
Mr Zelenskyy pleaded for the EU to rapidly make Ukraine a full member of the bloc.
His country was granted candidate status in June.
"For our people it's really important, it's a motivation to defend our state," he said.
Despite praising recent judicial reforms implemented during wartime, EU officials have said that Ukraine must respect lengthy admission procedures applied to all aspirant members.
"Some may want to speculate about the end game, but the simple truth is that we are not there yet," an EU official said.
Ukrainian Prime Minister Denys Shmyhal previously said he wanted the country to join the bloc in two years.
But he was more evasive when pressed by journalists on Thursday during a joint press conference with Ms von der Leyen.
"The decision made by 27 member states can take a while and we are conscious of this," he said.
Mr Shmyhal added that Ukraine had already implemented or was in the process of implementing the seven priorities laid out by the European Commission to move forward with its accession bid.
Ukraine is expecting an oral assessment in spring and a detailed report from the Commission in the autumn.
"I must say that the speed, the ambition, the determination that you have shown while being in an atrocious war to reach the goals you have set yourselves is impressive," said Ms von der Leyen as she stood next to Ms Shmyhal.
EU and Ukrainian officials in Kyiv will also discuss global food security and a 10-point peace plan set out by Mr Zelenskyy.
Ms von der Leyen said on arrival that "the EU stands by Ukraine as firmly as ever".
EU foreign affairs minister Josep Borrel is expected to announce on Friday that another 15,000 Ukrainian soldiers will receive European military training this year, increasing the total to 30,000.
EU officials have said he will also pledge €25 million ($27.4 million) to support Ukrainian demining efforts.
"When Ukraine has conquered territories temporarily occupied by Russia, we have discovered a broad use of anti-personnel mines," an EU official said.
"There is a huge necessity to deal with that to not put populations into deadly situations."
The EU's assistance to Ukraine has reached €50 billion since the start of Russia’s war.
As senior European officials arrived in Ukraine, rescue crews dug through the rubble of an apartment building in the east of the country that was struck by a Russian missile.
At least three people were killed in the attack and 20 others were wounded.
An EU official said Brussels supported Mr Zelenskyy's 10-point peace plan, which he presented in November at the G20 summit.
"We will work together using our diplomatic outreach ... to ensure widest participation and support for such an initiative," the official said.
Ukraine's government is also keen to receive more western military aid as new offensives loom. Germany and the US have pledged to send tanks and Kyiv is now asking for fighter jets.
US President Joe Biden has ruled out providing F-16s.
US Defence Secretary Lloyd Austin said on Thursday during a trip to the Philippines that his country was focused on sending artillery, armour, air defence and providing training to Ukrainian troops.
The US is “focused on providing Ukraine the capability that it needs to be effective in its upcoming anticipated counteroffensive in the spring”, he said.
“We’re doing everything we can to get them the capabilities that they need right now to be effective on the battlefield."