It is hard to pinpoint the exact date when it began, but it had certainly started by June 8 and the gains since then, according to the BBC, Ukraine reports,
Ukraine has confirmed it has started "counter-offensive and defensive actions" after an escalation in fighting in the south and east of the country sparked speculation about the widely anticipated push.
Officials claim to have taken seven settlements in the eastern Donetsk region and at least 90 sq km (35 sq miles) since starting their counter-offensive earlier this month.
How Russia's gradual gains in the face of fierce Ukrainian opposition have affected the front line in recent months.
www.bbc.com