BELGRADE, Serbia

Croatian President Zoran Milanovic on Wednesday said the ongoing Russia-Ukraine will face the most critical period amid the Russian president's announcement of partial military mobilization.

"This means the prolongation of the war in Ukraine because ... (Russian President Vladimir) Putin has received domestic political support because of this economic stability (unlike the expectations that Russia would weaken economically)," Milanovic told a conference in the capital Zagreb.

"However, after six months, we see that Russia is not in a position to do the impossible with a total of 150,000 professional soldiers. Now partial mobilization is going on because professional soldiers will be used as infantry."

Russia must get so weak that it cannot repeat what it has done in Ukraine, he said.

Asked if Croatia has a plan in case of a nuclear war, he said Croatia has not participated in key decisions and it is not a nuclear power.

"We are neither Poles, nor did we invade Ukraine, nor did we make key decisions. We joined NATO with the primary goal of the Americans protecting us from barbarism and danger from Belgrade. So, we are neither asked nor do we participate," Milanovic said.

Earlier, Putin announced a partial mobilization of reservists in Russia, calling up 300,000 reservists to join the army.

On Tuesday, Ukraine's Luhansk and Donetsk regions, and Russia-controlled parts of Zaporizhzhia and Kherson announced holding referendums on joining Russia on Sept. 23-27.