The Russian Army will be fully combat-ready only until the middle of May because of the rotation cycle of its conscripts, reports on Thursday said. If Russian President Vladimir Putin wants to mobilize troops into mainland Ukraine, he would have to do so soon or else wait months for the Red Army to be prepared for such a move again.

The reports coincided with video footage (see below) allegedly showing a substantial number of Russian tanks and soldiers moving toward Ukraine to reinforce the tens of thousands of soldiers already stationed there. The timing of these events has led to some speculation over whether the long-simmering frictions between Moscow and Kiev could come to a boil before mid-May, possibly even this weekend.

“Russian conscripts serve only one year,” npr’s Corey Flintoff reported on April 25. “[This means] they spend much of their time in training, and are only combat-ready for about half of their stint in the military.”

Flintoff quotes Pavel Felgenhauer, a Moscow-based military analyst saying, “That’s why it’s so important that we either move now, and order the conscripts to stay in units because of a war situation, or we don’t move at all.”

Felgenhauer explained that around half of the drafted troops are prepared to be discharged by mid-May, so unless Russia makes its move by then, the army will not be completely combat-ready again until sometime in August or September. This window could grant Ukraine the time required to improve its own outdated military forces, which could transform it into a slightly more dangerous adversary for the Russians.

Whether the conflict comes to a boil in the days ahead or not, these events are already having a profound impact on Europe. To learn the details and significance of the European response, read “The Crimean Crisis Is Reshaping Europe.”

A huge column of Russian armored vehicles moves toward the Ukraine border from the city of Rostov-on-Don, Russia, on April 24.