Ukrainian President Petro Poroshenko has said his country was not fighting a civil war in its east but was fighting "foreign mercenaries".
He hailed soldiers for forcing pro-Russian rebels out of several towns and cities.
As fighting raged around the rebel strongholds of Donetsk and Luhansk, Mr Poroshenko awarded members of the newly formed National Guard with medals for service.
Kiev has accused Moscow of sending the rebels fighters and weapons across its porous border with Ukraine, a charge which Russia denies.
But some battalions have openly said they were made up of volunteers from various countries, including Russia.
Ukraine's army has forced the rebels back towards the cities of Donetsk and Luhansk.
Separatists there have boosted their defences, and fighting has raged since a Malaysian airliner was downed last week.
Malaysian Prime Minister Najib Razak has said he will meet Dutch Prime Minister Mark Rutte next week.
They will discuss how to secure full access for investigators to the site in Ukraine where Malaysia Airlines Flight MH17 was downed.
They will also discuss the deployment of 30 investigators it said were needed to conduct a full investigation.
Mr Najib said pro-Russian rebels in control of the site had fulfilled two conditions in a deal reached with Malaysia.
The deal was to return the bodies of the victims and the aircraft's two "black boxes", but a full investigation is yet to take place.