Nata will set up what it is calling 'command units' in six eastern European countries. It denied that the move should be considered provocative by Russia.
The move comes as the head of Nato said that Russia's 'disturbing actions' in Ukraine had threatened Europe's security environment, and that recent victories by Ukrainian separatists could be directly linked to the shipment of Russian arms.
France's President Hollande called for a political solution in eastern Ukraine - and said sanctions would be maintained until there is one. Political Correspondent Carl Dinnen reports on the increasing diplomatic pressure on Russia over the conflict.
At least 12 civilians have been killed in the eastern Ukrainian city of Donetsk Donetsk today, Associated Press reported, citing city officials.
Five people were killed in a shell attack on a cultural centre in Donetsk as they waited for humanitarian aid, while two civilians were killed nearby when a mortar shell landed near a bus stop.
Five other people died in "sporadic artillery fire" in the west of the pro-Russian separatist stronghold.
The Ukrainian military blamed separatists for the attack on the cultural centre, saying they had used "a cynical terrorist act" to try to undermine a meeting of the so-called 'contact group' involving Ukraine, Russia and the Organisation for Security and Cooperation in Europe, as well as rebel leaders.
Andre Luzganov, who shot dramatic video of the attack the weekend, told ITV News his family has left and will not be returning to Mariupol.Read the full story ›
Alexey Chaban has become an internet hero after a Facebook post with a touching letter to the mother of a Russian soldier he spared.Read the full story ›
Nearly 500 coal miners were trapped in a mine in eastern Ukraine after a mortal shell hit a power station, Agence France Presse reports.
The Zasyadko pit in Donetsk - one of the largest in eastern Europe - lost power earlier today, leaving 496 stuck underground, a regional official told the news agency.
Russia's Sputnik news agency reports that more than 100 have now been rescued, citing a spokesperson for the rebel-led Donetsk People's Republic.
The Foreign Secretary has called on Russia to halt its support of pro-Russian rebels who have launched a huge new offensive in eastern Ukraine.
President Obama also condemned what he called the "Russian backing, Russian training and Russian troops" supporting the separatists.
You may find some parts of Neil Connery's report disturbing.
Further violence by Russian-backed separatists in Ukraine will lead to a "grave deterioration" in relations between the European Union and Moscow, Foreign Secretary Philip Hammond has warned.
Mr Hammond called on Russia to end its support for the separatists and exert its influence over the rebel leadership to bring an end to the attacks.
I am deeply concerned about the significant escalation in violence in east Ukraine over the past week. Recent announcements by the separatist leaders of further offensives, and their blatant refusal to abide by the ceasefire, raise serious questions about the commitments they made at Minsk.
I call on Russia to stop its material support to the separatists immediately, and use its considerable influence over the separatist leadership to stop these indiscriminate attacks, and fully abide by the commitments they made at Minsk.
Russia will be judged by its actions, not words. If the escalation in fighting continues, with tragic consequences for the local population, this will lead to a further grave deterioration in relations between the EU and Russia.
The European Union will summon foreign ministers of its 28 member states for an emergency meeting to discuss renewed fighting in Ukraine on Thursday, Foreign Affairs chief Federica Mogherini said.
East Ukraine has seen all out war return in recent days since pro-Russian rebels announced the effective end of a five-month ceasefire and the start of a new offensive.
They launched an assault on Saturday on Mariupol, a port of 500,000 people, the largest city still under government control in two rebellious eastern provinces.
Shocking dashcam footage appears to show the moment shells exploded in the streets of the eastern Ukrainian city of Mariupol yesterday.
At least 30 people were killed and more than a hundred injured when rocket fire rained down on the area yesterday.
The Ukrainian president has described the shelling as a terror attack, while Nato and the US demanded Russia withdraw support for rebels in the region.
Russia says it does not support the rebels, but Western governments say the amount of heavy weaponry in their possession suggests otherwise.
At least 30 people have been killed in a residential area of Mariupol, eastern Ukraine, by rocket attacks launched by pro-Russian rebels.
NATO said fighting in the area has sharply escalated "in utter disregard of the ceasefire."
Russian troops were using sophisticated missiles, rockets and drones at multiple locations in Donetsk and Luhansk as well as Mariupol, Secretary-General Jens Stoltenberg said.
Russian troops in eastern Ukraine are supporting these offensive operations with command and control systems, air defence systems with advanced surface-to-air missiles, unmanned aerial systems [drones], advanced multiple rocket launcher systems and electronic warfare systems.
I strongly urge Russia to stop its military, political and financial support for the separatists, stop destabilising Ukraine and respect its international commitments.
Russia denies having troops in eastern Ukraine.