Tusk, who arrived in the Belgian capital on Wednesday evening, will also meet Ukrainian President Volodymyr Zelensky on Friday, his office said.
The two-day summit opens on Thursday.
Speaking on Monday after talks with Norwegian Prime Minister Jonas Gahr Stoere, Tusk said Europe needed to do more than just keep the existing measures in place.
“Today it is very clear that any attempt to loosen sanctions on Russia, to shorten the list of names, will only embolden the Russians," he said. "The problem is that sometimes some want to forget that it was Russia that caused the situation in which we have to sacrifice quite a lot and pay for our own security."
He said he would call on EU leaders to stop thinking about sanctions in narrow national terms and to present a united front, particularly given what he called "ambiguous signals" from Washington.
He was referring to US President Donald Trump’s announcement of a deal with Russian President Vladimir Putin under which Russia would supply nearly 5 million tonnes of diesel to world markets.
Energy prices are also on the agenda of the EU summit.
According to the European Commission, leaders will give it guidelines on temporary, targeted measures to ease the burden on households and businesses, and discuss a longer-term plan to reduce reliance on fossil fuels.
Leaders will also begin to tackle the EU’s next long-term budget, covering 2028-2034.
European Council President António Costa said talks this month should lock in the key elements needed for a final deal by the end of 2026, which he called crucial to giving economies "predictability and stability."
Migration is the other major item. Leaders will work from a five-point Commission plan that includes a new crisis response mechanism, a stronger Frontex border agency, better early warning and faster returns of people with no right to stay in the EU.
The plan also raises the possibility of temporarily suspending the right to asylum in a crisis.
Tusk will also attend an informal migration meeting on Friday morning at the invitation of the leaders of Italy, Denmark and the Netherlands.
(jh/gs)
Source: PAP