Update | Leaders at Nato summit agree to form eastern European rapid reaction force

In an effort to counter Russian aggression, Nato leaders approved plans yesterday to set up a rapid reaction force in eastern Europe comprising several thousand troops.

Nato Secretary General Anders Fogh Rasmussen said the new unit would send a clear message to potential aggressors.

"Should you even think of attacking one ally, you will be facing the whole alliance," he declared as a two-day Nato summit in south Wales drew to a close.

The agreement on the rapid response force was the cornerstone of discussions at the summit on how to combat Russia's provocations in Ukraine.

While Ukraine is not part of the Nato alliance, Russia's actions have prompted fears among member countries in central and eastern Europe that the Kremlin could seek to make gains within their borders as well. The force will include land, air and sea assets, and is likely to number about 5,000 troops.

The announcement came as Ukrainian President Petro Poroshenko voiced "careful optimism" that talks with pro-Russian separatists in the Belarusian capital, Minsk, would set the course for a ceasefire after more than five months of fighting.