Ukrainian President Petro Poroshenko speaks during the opening of the extraordinary sitting of the National Security and Defence Council in Kiev on August 28, 2014. A senior NATO official said on Thursday that 'well over a thousand' Russian troops were operating inside Ukraine. 'They support separatists, fighting with them and fighting amongst them,' the official said on condition of anonymity, adding that the supply of arms by Russia had increased in both 'volume and quality'. SERGEI SUPINSKY/AFP/Getty Images

Ukrainian authorities accused Russia of invading Ukraine Thursday, prompting President Petro Poroshenko to cancel a visit to Turkey to meet with security advisers. Col. Andriy Lysenko, a spokesman for Ukraine's security council, said two columns of Russian tanks, infantry and other vehicles crossed the border and entered nearby Novoazovsk after rockets were fired at Ukrainian forces from Russian territory.

UPDATE 12:41 p.m. EDT: Ukrainian President Petro Poroshenko: "We are capable of protecting ourselves... We must keep calm, stay cold-minded, strengthen our unity and international solidarity."

Poroshenko hinted at international action, saying "a series of resolute actions... from our key strategic partners in the world gives us some cautious grounds for stabilization of the situation."

"Panic is the same weapon as tanks, APCs and AK rifles," Poroshenko said. "It destabilizes the situation in the country without advancing inland"

UPDATE 11:52 a.m. EDT: NATO released aerial images of Russian troops engaging in operation in Ukraine.


Novoazosvk, a port city along the Sea of Azov, lies on the southern end of separatist territory less than 10 miles away from the Russian border. A separatist flash offensive began on Wednesday and came from the direction of the Russian border in an area accessible only by crossing government territory or coming from across the Russian border, according to locals.

An Associated Press reporter saw separatist checkpoints around Novoazovsk and was told he could not enter the city. The city lies along a highway leading to Mariupol, which Ukrainian government forces recaptured in June, and runs down to Crimea, which Russia annexed in March.

The fresh accusations came just two days after Poroshenko met with Russian President Vladimir Putin, prompting hopes that a peaceful end to the conflict would be brokered shortly. Poroshenko spoke of a “roadmap” to peace, while Putin said managing peace was squarely the responsibility of the Ukrainian government.

Aleksandr Zakharchenko, prime minister of the self-proclaimed Donetsk People’s Republic, said on Russian television that up to 4,000 Russians, including soldiers on leave from active duty, had fought for separatists in eastern Ukraine. Ten regular Russian paratroopers were captured by Ukrainian forces on Tuesday, just as Poroshenko and Putin met. Ukraine’s National Security and Defense Council said Russian troops had replaced rebel fighters in Luhansk.

Over 2,500 people have been killed in the fighting in eastern Ukraine since April, including 300 civilian passengers aboard Malaysian Airlines Flight MH17, which was shot down over separatist-held territory on July 17.