Russian President Vladimir Putin on Thursday ordered the Russian military to increase the number of troops by 137,000 to a total of 1.15 million amid Moscow’s military action in Ukraine. Putin’s decree, which takes effect on Jan. 1, did not specify whether the military would bolster its ranks by enlisting more conscripts, increasing the number of volunteer soldiers or using a combination of the two. But some Russian military analysts predicted it would rely heavily on volunteers, a cautious stance that reflects the Kremlin’s concerns about potential fallout from a troop surge. The presidential decree will increase the total number of Russian military personnel to 2,039,758, including 1,150,628 soldiers. An earlier order put the army’s numbers at 1,902,758 and 1,013,628 respectively in early 2018. The Kremlin has said only volunteer contract soldiers are taking part in what it calls a “special military operation” in Ukraine, rejecting claims it is considering a mobilization. Russian media and non-governmental organizations say Russian authorities have tried to boost the number of troops involved in military action in Ukraine by attracting more volunteers, engaging private military contractors and even offering amnesty to some prisoners in exchange for a tour of military service. Regional authorities also tried to help strengthen the ranks by forming volunteer battalions to be deployed in Ukraine. All Russian men aged 18-27 must serve a year in the army, but a large percentage avoid the military for health reasons or deferments granted to students. The share of men who avoid the draft is particularly large in Moscow and other large cities. The Russian military gathers draftees twice a year, starting on April 1st and October 1st. Putin ordered the draft of 134,500 conscripts during the last spring draft earlier this year and 127,500 last fall. In recent years, the Kremlin has emphasized increasing the share of volunteer contract soldiers as it sought to modernize the military and improve its capabilities. Before the Kremlin sent troops into Ukraine on February 24, the Russian military had more than 400,000 contract troops, including about 147,000 in ground forces. The number of conscripts has been estimated at about 270,000 and the rest have been commissioned officers and non-commissioned officers. Military analysts say that if the campaign in Ukraine continues, those numbers could be clearly insufficient to support operations in Ukraine, which has declared a goal of forming an army of 1 million. However, many observers have warned that a widespread mobilization or a sweeping increase in the number of lottery ticket holders could fuel public discontent and destabilize the political situation in Russia. This happened during the separatist wars in Chechnya in the 1990s and early 2000s, when poorly trained Russian soldiers were sent into battle and suffered heavy casualties. Retired Viktor Murakovsky noted that Putin’s order on Thursday reflected pressure to fill the ranks amid military action in Ukraine. In comments to the online news agency RBC, he charged that the Kremlin would likely try to continue relying on volunteers and predicted that they would account for most of the Kremlin-ordered increase. Another Russian military expert, Alexei Leonkov, also said the authorities would not expand the camp and increase the number of troops by hiring more contract soldiers. “The new military equipment has become more complex and the people who operate it need training for at least three years,” Leonkov was quoted as saying by the state-run RIA Novosti news agency. “A draft won’t help with that, so it won’t increase the number of draftees.”