Top military officials found it difficult to conceal their bafflement and concern Thursday following the reports that Defense Minister Moshe Ya'alon will soon be made to step down in favor of Yisrael Beytenu leader Avigdor Lieberman. The prevalent assumption among defense officials is that, despite his well-crafted tough-talking image, Lieberman will be a pragmatic defense minister who is likely to show the defense establishment and its captains the respect they deserve, and that he will listen, learn, and try to prove that he is far more prudent than he seems to be. Still, even if this turns out to be the case, reality may present Lieberman with significant challenges. The defense establishment is currently the most pragmatic, impartial, and stabilizing factor in the Israeli governmental system. It is what is preventing an escalation in the Gaza Strip; maintaining security coordination with the Palestinian Authority in Judea and Samaria and solid ties with Egypt and Jordan; preserving the strategic alliance with the U.S. in days clouded by disharmony between the leaders; and, most recently, representing the solid, unwavering ethical foundation of Israeli society. One has to wonder how Lieberman will react to the first rocket fired at Israel, or the first stabbing attack. Will he allow rogue MKs to ascend the Temple Mount? Will he allow settlers to build illegal outposts in Judea and Samaria? Or will he sign administrative arrest orders against suspected Jewish terrorists, and prioritize Israel's vital ties with the U.S., even at the expense of the interests serving his Russian friends? Lieberman's new role will no longer allow him to get away with rhetoric -- he will have to make decisions. An ill-worded statement, an imprudent decision, or a defiant move could lead to a security escalation and cost lives. Ya'alon was experienced enough to avoid the land mines. One can only hope that Lieberman's learning curve will not come with too hefty a price. In this context, Lieberman's nonexistent military past is irrelevant. Israel has had some excellent civilian defense ministers, as well as its share of generals who proved less successful in the role. The recipe for success here is to know how to listen, to seek expert advice, to work hard, to surround yourself with professionals, and most importantly, to remember that there are human lives -- not just words -- at stake. Lieberman will also have to adjust to the fact that he is running a powerful apparatus, one much greater than his party, and that he will have to serve as this mechanism's suit of armor. As one whose last appearance in a military installation involved attending a military court hearing in support of a soldier accused of killing an immobilized terrorist, Lieberman has his work cut out for him as he tries to convince the General Staff that it can count on his backing and support. If Lieberman fails to convince the military of this, if he tries to bend or break the IDF, to shape it to his liking, he will find himself facing formidable opposition led by the chief of staff. The General Staff has already proved it will not cower before the government, and it will not start doing so now.