(QHA) -

Annexation of Crimea was the most significant event of the year. EU Council President Herman Van Rompuy said this addressing the UN General Assembly Sept 25.

“Considering this year, sudden annexation of Crimea in March became the most impressive act for Europe. Violation of Ukraine's sovereignty and territorial integrity by Russia has triggered the gravest treat to the European security order in decades”- Rompuy noted.

He also stressed the need for Kyiv to "move firmly" forward on the path of economic, political, and constitutional reforms. Those reforms, he said, will determine the success of "a lasting political solution."

Meanwhile, the leaders of the world's most developed economies, G7, September 25, vowed to stand by Ukraine and warned Russia more sanctions could follow unless a ceasefire is implemented.

In a draft version of a statement to be issued later Thursday, G7 leaders will tell Moscow that a slew of crippling EU, US and Canadian sanctions can only be rolled back once all the terms of a truce agreed with Kiev are put into effect.

Crimea  was annexed by Russia in March, after local referendum on region's status was held. The move, however is recognized illegitimate by EU, US and Kyiv.