Ukrainian army

The G7 group of economic powers has agreed to intensify sanctions on Russia over its actions in Ukraine.

A G7 statement gave no detail of the sanctions, but US officials said they could announce measures by Monday, reports BBC.

Meanwhile, negotiators are trying to secure the release of international observers seized by pro-Russia gunmen.

Three people were killed in a shooting at a checkpoint in the Ukrainian town of Slaviansk, reports the Russian channel Rossiya 24.

Another was taken to hospital in serious condition.

Slaviansk is one of the east Ukrainian cities, occupied by pro-Russian separatists.

The Ukrainian army has stormed Kramatorsk Airfield in Donetsk region, in a moved that has marked the beginning of a long-forewarned "anti-terrorist operation".

A series of shots and explosions could be heard in the area, according to reports by the local newspaper Novosti Kramatorska cited by Lenta.ru.

Another Ukrainian base in Crimea overrun

KIEV -- Russian troops and self-defense units of Crimea have taken control of another Ukrainian marine base in Crimea, this time in Feodosia.

According to reports quoting officials in Kiev, the troops "used stun grenades and APC" as they overrun the installation located in western Crimea.

Armed Russian forces arresting Ukrainian army officers during an operation in Simferopol on Tuesday.

Greece’s prime minister and foreign minister walked a careful line on Tuesday between backing the European Union’s position on Crimea but also insisting that attempts should continue at reaching a diplomatic compromise with Russia over the Ukrainian region.

Ukraine "has no plans to join NATO" - Yatsenyuk

KIEV -- Ukraine's new Western-backed prime minister said on Tuesday in a televised address that his country had no plans to join NATO.

Arseniy Yatsenyuk said that “for the sole purpose of preserving the unity of Ukraine, the issue of accession to NATO is not on the agenda," AFP reported.