Ukrainian President Petro Poroshenko has said that one of the key challenges for Ukraine is Russia's aggression that continues for over two years.

The president's press service reported that Poroshenko said this at a first meeting of the International Advisory Council on Saturday.

The president said that it is important that international solidarity and unity is maintained, as Russia continues its hybrid war, combining the open military campaign with psychological ware – propaganda and terrorists' attacks.

"The coordinated position of the whole world, G7 and the EU on sanctions is vitally important. We stick to the implementation of the Minsk agreements and insist that Russia fulfills all their provisions," the Ukrainian president said.

He said that sanctions are needed as a tool to press on Russia and stimulate it to sit down at the negotiating table and convince it to remove Russian military and all weapons from Ukraine, return control over the border, ensure the conditions for free and fair election and restore Ukrainian sovereignty on the occupied territories.

Poroshenko added that councils of representatives of the International Advisory Council are important for Ukraine in this sphere.

The Ukrainian president also said that before the war began, five million people lived in Donbas.

"Europe has not faced such large catastrophes for many years. This is larger than Transdniestria, Ossetia and Abkhazia," he said.

Former Prime Minister of Australia Tony Abbott noted fight of Ukrainians for their national survival and a possibility of adhering to the selected way. He also said that it is important that other countries sustain the Ukrainian state. He reminded Australia's assistance in the form of supplies of nonlethal weapons worth $5 million and joint military drills.

Of course, this is your battle, but we have a feeling that this is our battle too, as when freedom is suppressed in one part of the world, this means that it is suppressed in the whole world, he said.

Ex-foreign minister of Poland Radoslaw Sikorski said that it is important for Ukraine to focus on reforms and continue effective fight against corruption.

Head of the European Parliament Committee on Foreign Affairs Elmar Brok, in turn, said that it is also important to ensure communications between Ukraine and European countries. He said that the Minsk agreements managed to contain Russia's aggression, although they have not brought the solution of the problem.

He said that aggression must cost an arm and a leg for the aggressor and this can be accomplished only by sanctions.

Brok said that Ukraine must continue reforms that would confirm its ability of being a successful state.