The presence of Russian soldiers in southeastern Ukraine “is unacceptable, irresponsible and absolutely reckless,” Foreign Affairs Minister John Baird said Thursday, the same day reports suggested Canadian fighter jets will soon be on patrol closer to Russian airspace.

Four of six CF-18s that Canada sent to Eastern Europe earlier this year have arrived at Siauliai Air Base in Lithuania, the Canadian Press reported. They will begin protecting air space over Lithuania, as well as Latvia and Estonia, next week, working alongside jets from Portugal, Germany and Belgium.

The international mission is designed to protect Eastern Europe allies amidst Russia’s ongoing incursion into eastern Ukraine, which heated up Thursday with reports of Russian soldiers in the southeast.

“We can confirm that Russian military boots are on Ukrainian ground,” Ukrainian President Petro Poroshenko said as he helmed an emergency meeting of his country’s national security council. Reports from the southeast suggested that two columns of Russian tanks had rolled into the area, as heavy shelling left 15 civilians dead in the rebel-held city of Donetsk.

Baird calls advances ‘absolutely unacceptable’

“It is no surprise to anyone that there are both Russian and Russian-sponsored units actively operating within Ukraine’s sovereign borders,” Baird said Thursday in a teleconference with reporters from Croatia.

“What we’ve seen in the last couple of days is a marked escalation of that.”

In May, Prime Minister Stephen Harper said he feared a “slow-motion invasion” of Ukraine by Russian troops, Baird noted.

“It appears that the Russian Federation is starting to turn up the speed on that. This is absolutely unacceptable, irresponsible and absolutely reckless. It is also deeply and shamelessly dishonest.”

Baird urged Putin to rein in his country’s military action and stop the flow of arms and other support to rebels.

Canada will consider further sanctions against Russian nationals, Baird said, but did not elaborate.

NATO has confirmed the presence of more than 1,000 Russian soldiers in Ukraine, in addition to tanks and artillery. Thousands more have been spotted gathering at the border.

"Over the past two weeks we have noted a significant escalation in both the level and sophistication of Russia's military interference in Ukraine," said Dutch Brig.-Gen. Nico Tak.

"We have also detected large quantities of advanced weapons, including air defence systems, artillery, tanks, and armoured personnel carriers being transferred to separatist forces in Eastern Ukraine."

Vadym Prystaiko, Ukraine’s ambassador to Canada, said Thursday that sanctions will be “helpful to some extent.” However, what Ukraine needs now is military support from its allies, just as Russia is arming separatist rebels.

“Russia is not shying away from helping separatists with everything they have: anti-aircraft missiles, tanks, everything,” Prystaiko told CTV News Channel. “So far we are not receiving any military assistance.”

Some allies have provided helmets and other “simple stuff,” he said, but “we need something to fight troops with. Real ammunition, real tanks and aircraft.”