The Verkhovna Rada, Ukraine's parliament, approved the bill on Tuesday.
According to the new law, the Ukrainian government is authorized to call upon "people liable for military service and reservists and the supply of transport to meet the needs of the Ukrainian Armed Forces, the Ukrainian National Guard, the Ukrainian Security Service, the Ukrainian State Border Guard Service, the State Special Transport Service, and other Ukrainian military units in the volumes determined by the mobilization plans."
Partial mobilization may begin within 45 days.
The Ukrainian government moved forward with authorizing partial mobilization, the legislation states, because of unrest in Ukraine's east and provocations by neighboring Russia.
On Wednesday, National Security and Defense Council spokesman Andrey Lysenko reported Russian forces continued to amass near the border, including "units of the 32nd motorized infantry brigade, the 24th separate special purpose brigade of the main intelligence directorate of the Russian General Staff in Novosibirsk region, as well as the 56th engineer general service regiment of the Republic of Tatarstan."
NSDC Secretary Andrey Parubiy projected that the new law authorizing partial mobilization would enable the deployment of "15 military units and 44 combat support units in combat condition."