Ukraine has long been lobbying for its allies to allow long-range attacks on targets inside Russia while also pressing for an invitation to join the NATO military alliance.
Allies including the United States have been unwilling to permit long-range attacks for fear of further escalating the conflict, and some are opposed to inviting Ukraine to join NATO.
"We discussed issues of long-range strikes and Euro-Atlantic integration. And here we also are cautiously optimistic," Sybiha said in televised comments.
Kupiansk was seized by Russian forces in the early days of the war but retaken by Ukrainian troops. (AP PHOTO)
Sybiha said his talks in Brussels had also touched on military aid.
"We have a clear picture - a clear timeframe, clear volumes – of what will be delivered to Ukraine by the end of the year. This helps us strategically to plan our actions on the battlefield," he said.
The assistance, he added, would include weapons and funds for arms production deals.
Ukrainian forces on Wednesday repelled an attempt by Russian troops to pierce defences near the northeastern city of Kupiansk, Ukraine's General Staff said.
The General Staff report, posted on Facebook, said Russian forces attacked in four waves and deployed about 15 pieces of equipment including tanks, armoured vehicles and a mine-clearing system.
"With skilful and decisive actions, our defenders stopped the enemy, destroyed all of its armoured vehicles and eliminated a significant portion of its personnel," the report said.
Some of the Russian forces, it said, had donned uniforms resembling those of the Ukrainian military, a practice it characterised as amounting to a war crime.
Kupiansk, east of Kharkiv was seized by Russian forces in the early days of their February 2022 invasion but was recaptured by Ukrainian troops in a lightning counter-offensive later in the year.
Russian forces have in recent months been active in the area.
