He does not ask, he agrees to a truce. There are two big differences here.
The Kremlin has dirt on Trump and he is trying to save Putler.
Therefore, a diplomatic game is being played, because the touchy Trump can seriously ruin the war. It just so happened that after WWII, the main arms producers were the USSR and the USA. Smaller countries depended either on licenses or on supplies. Western countries do not have excess weapons, unlike Russia, which inherited the military reserves of the USSR. Although Putler does not have enough of them, if he buys weapons from the DPRK.