Well, what goes around comes around.

Overnight, according to a report in the Interfax news agency, Russia alleged that over 400 Ukrainian troops crossed the border into Russian territory.

The Associated Press reported on Monday that it is unclear why the raid occurred, as both sides are offering conflicting accounts of the motivation for the incursion.

The Russian official said the soldiers deserted the Kiev government and the Russian side opened a safe corridor, while a Ukrainian military official said the soldiers, without giving a number, were forced into Russian territory by rebel fire after running out of ammunition.

This is not the first Ukrainian intrusion into Russian territory. “Last week, a group of about 40 men from Ukraine’s 51st Mechanized Brigade crossed into Russia,” The Washington Post reported on Sunday. “They have since returned to Ukraine of their own volition and at least some are being accused of desertion.”

The Russian defense industry revealed on Monday that it plans on holding military exercises on the Ukrainian border this week. Those exercises will focus on air readiness, according to the BBC, which reported that the drills will involve over 100 military aircraft including “Sukhoi Su-27 and MiG-31 fighter jets, Mi-24 and Mi-28 helicopters and Russia’s newest frontline bomber, the Sukhoi Su-34.”

Combined with the reported 15,000 Russian troops amassed along the Ukrainian border, fears are growing that Moscow may choose to mount an outright invasion of the eastern and southern parts of Ukraine where separatist fighters rages.

However, as Andrew Bowden wrote last week in Foreign Policy, Russian President Vladimir Putin may be taking on more than he bargained for with a full-scale invasion:

Russia does not have the force ready at the border for a full-scale invasion and occupation of eastern Ukraine. But it doesn’t need to. Putin does not want to annex the large and economically depressed region, despite the increasingly vocal calls from Russia’s nationalist right and the Russian commanders in charge of the insurgency. Even if he did, from a strategic point of view, he has missed his best opportunity. In May and June, Russia had its best units poised and positioned on Ukraine’s borders. Since then, however, the rotation of conscripted soldiers has put fresh, less-than-battle-ready soldiers into the field.

Of course, analysts wrote similar warnings about Russia’s intention to invade and annex the Crimean Peninsula – an indebted and cut off region with little economic value in spite of obvious strategic worth. In the end, peninsula’s the strategic usefulness led Russia to absorb the economic consequences of invading Ukrainian territory.

From a Western perspective, creating negative economic pressure on the Kremlin and on the Russian people may still force Putin to rethink the sense of his gambit in Ukraine. After nearly half a year of economic warfare against Russia, Putin has only escalated the situation on that European battlefield.