Angered by the death of a state security officer and the wounding of two of his comrades near the flashpoint eastern city of Slaviansk, Turchynov gave rebels occupying state buildings until Monday morning to lay down their weapons.
He blamed Russia, which opposed a pro-Europe uprising that forced Moscow-backed former president Viktor Yanukovych to flee, for being behind the rash of rebellions across Russian-speaking towns in eastern Ukraine.
The blood of Ukrainian heroes has been shed in a war which the Russian Federation is waging against Ukraine, he said in an address to the nation. The aggressor has not stopped and is continuing to sow disorder in the east of the country.
With East-West relations in crisis, NATO described the appearance in eastern Ukraine of men with specialised Russian weapons and identical uniforms without insignia - as previously worn by Moscows troops when they seized Crimea as a grave development.
Though the Ukrainian military did not resist the Russian takeover of Crimea with force, Turchynov threatened robust action against the rebels in the east. The National Security and Defence Council has decided to launch a full-scale anti-terrorist operation involving the armed forces of Ukraine, he declared.
Ukraine has repeatedly said the rebellions are inspired and directed by the Kremlin. But action to dislodge the armed militants risks tipping the stand-off into a new, dangerous phase as Moscow has warned it will protect the regions Russian-speakers if they come under attack.
One Ukrainian state security officer was killed and five were wounded on the government side in Sunday's operation in Slaviansk, interior minister Arsen Avakov said.