Ukraine expects its fight to regain land lost to the Russian invasion to be long and grinding, a senior presidential aide in Kyiv told AFP Wednesday. 

Moscow's forces still occupy swathes of southern and eastern Ukraine and over a month into Kyiv's long-anticipated counteroffensive, large parts of the front appear to be frozen. 

Speaking to AFP, presidential aide Mykhailo Podolyak admitted progress was "slower than we want."

"Undoubtedly, this operation will be quite difficult, long and will take quite a lot of time," he said. 

But he maintained that Ukraine seeks to "regain the 1991 borders, including the territory called the Crimea peninsula" that is currently annexed by Russia. 

Kyiv's army is facing a number of difficulties on the battlefield, he said.

Ukrainian forces are facing heavily mined territory, logistical problems such as in arms deliveries, and Moscow's superiority in parts of the skies.

"Let's be objective, Russia has the advantage in the air above the front," Podolyak said. 

Kyiv would need an additional 300 armoured vehicles and dozens of F-16 fighter jets to accelerate the offensive, he said.  

"Of course, we need additional armoured vehicles -- two to three hundred tanks first of all," Podolyak told AFP journalists. 

"We need up to 80 F-16 planes in order to close the skies well, especially in the area near the front."

But he also reported some success, saying the number of "offensive operations" led by the Ukrainian army was "progressively rising" and that not all brigades readied for the counteroffensive have been sent to battle. 

He said that the "pressure was mounting" on Russian forces and that Kyiv wanted to "inflict tactical defeats and cut off Russian troop groupings." 

The high-ranking official, known for his outspoken comments, hoped that the offensive "may at some point collapse the Russian defence in one direction or another, and in that case events will develop quite quickly."

- Seeking Black Sea patrol -

Podolyak also said Kyiv was seeking a joint military patrol of Black Sea countries in order to continue grain exports from its ports after Russia exited a landmark deal ensuring the safety of cargo ships.  

He spoke two days after Moscow left the deal and Russia pounded Ukrainian Black Sea port infrastructure for two straight nights.

"Negotiations are ongoing at all levels. A UN mandate should be added here to create a military patrol that would include countries in contact with the region, for example Turkey, Bulgaria or any others," Podolyak said. 

Ukraine has said it is ready to continue grain deliveries via the Black Sea even after Russia's exit from the agreement.

Moscow's withdrawal was deplored by the West and the UN.  

On Wednesday, Kyiv said Russia was targeting grain terminals on the Black Sea and that it had destroyed 60,000 tonnes of the vital footstock that was meant for export. 

Podolyak said Moscow "deliberately destroys infrastructure in ports where the grain is exported."

He said Russia does not hit foreign ships as it would lead to "consequences" but that it "wants to destroy grain (loading) infrastructure, not the transport infrastructure". 

Podolyak spoke hours before the Russian army warned that cargo ships en route to Ukrainian ports would be regarded as possibly carrying military cargo from Thursday. 

- Compromise would 'destroy' Ukraine -

Sixteen months into Russia's invasion of Ukraine, Podolyak said that any compromise with Russia to end the war would "destroy" Kyiv's statehood as Moscow "hates" Ukraine and seeks to recreate the Soviet Union.  

Kyiv has slammed some Western countries that have suggested it should give up some territory to end the war. 

"For us a compromise does not exist because Russia hates us, it came to destroy the concept of the Ukrainian state," Podolyak said. 

"We hate the Russians because they quite simply kill us." 

He said that giving in to Moscow would lead to the "slow loss of Ukraine and its statehood". 

"Maybe not in three days, but in three years or five."

He said President Vladimir Putin's Russia wanted to recreate the USSR. 

"A compromise would mean that the Soviet Union would be back."  

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