Bulgarian Foreign Minister Daniel Miltov
The crisis in Ukraine puts into question the principles underlying European security, Bulgarian Foreign Minister Daniel Mitov was quoted as saying in a ministerial statement Friday.

On Thursday, an informal meeting of the foreign ministers of the Organization for Security and Co-operation in Europe (OSCE) states was held in Potsdam, Germany. The meeting focused on current security challenges and practical steps to overcome them.

"The Bulgarian foreign minister stressed [at the OSCE meeting] that the crisis in Ukraine and around it puts into question the fundamental principles on which European and Euro-Atlantic security is based... A sustainable political solution to the crisis must be based on the principles of sovereignty, territorial integrity, unity and Ukrainian independence," the ministry said in a statement.

According to the statement, the OSCE ministers also discussed the settlement of issues in Georgia, Transnistria and the Nagorno-Karabakh region, as well as the EU migration crisis, anti-terrorism measures and energy security.

In April 2014, Kiev authorities launched a military operation to suppress independence militia in the eastern Ukrainian Donbas region. In February 2015, the two sides reached a ceasefire deal after talks brokered by the leaders of Russia, Germany, France and Ukraine - the so-called Normandy Format — in the Belarusian capital of Minsk.

Key points of the Minsk agreements include a ceasefire, heavy weapons withdrawal from the line of contact in eastern Ukraine, constitutional reforms, including a decentralization of power in the country, and granting a special status to the Donbas region.