Four former Soviet satellites in Central Europe signed a military pact Friday to coordinate defence planning and to create a joint combat unit to operate under NATO and EU auspices, in response to the Ukraine crisis.

“The current situation in Europe shows that unfortunately a military conflict, previously considered unthinkable, could happen,” Polish Defence Minister Tomasz Siemoniak said at a meeting of the Visegrad 4 (V4) group of countries — the Czech Republic, Hungary, Poland and Slovakia.

Speaking in Visegrad, Hungary, he said the Ukraine crisis showed the importance of “more dynamic cooperation” between the V4 countries within NATO and the European Union.

The “V4-EU” combat unit would only be ready to take part in NATO or EU operations by 2016, however, he said, adding that V4 military cooperation was “unique” within the NATO miliary alliance.

Europe’s defence capabilities can be “improved,” he told a news conference.

Hungarian Defence Minister Csaba Hende said that the joint body would comprise 3,000 soldiers contributed by the four countries.

“It would operate as a regional unit within NATO or EU operations,” he added.

Friday’s deal, signed by the defence ministers of all four countries, also included commitments on joint military exercises and defence spending coordination.

The V4 group was set up in 1991 as a forum for its members — all former communist countries and current EU members — to discuss common security and energy issues.

Hungarian Foreign Minister Janos Martonyi said Thursday that the V4 members are particularly “vulnerable” to the Ukrainian situation, would be hurt by EU sanctions against Russia and would expect “solidarity” from other EU member states.

Poland, Slovakia, and Hungary all have borders with Ukraine as well as significant minorities living there, mostly in the western part of the crisis-wracked former Soviet state.