Donald Trump says he knows a bad deal when he sees it, and Vladimir Putin is offering him one on Ukraine. That’s the meaning of this week’s escalation by Kremlin-backed rebels in eastern Ukraine that has resulted in some of the worst fighting since the Russian strongman launched his invasion in 2014.

At least 12 Ukrainian soldiers have been killed since Monday in clashes around the government-held city of Avdiivka, north of the Russian-occupied Donetsk region. The Organization for Security and Cooperation in Europe, which oversees implementation of a 2015 cease-fire agreement, says it has recorded more than 10,000 explosions in the area in recent days. Civilians, including 2,500 children, are caught in the crossfire without basic services.

The cease-fire agreement, known as Minsk II, prohibits the use of heavy artillery and requires the parties to withdraw heavy weapons. The Kiev government says the Russian-backed separatists are firing Grad rockets and heavy artillery.

Mr. Putin accuses Ukrainian forces of doing the same, but that reveals the main flaw of Minsk II, which is that it treats the warring parties as moral equivalents. The accords, negotiated by Angela Merkel and François Hollande and supported by the Obama Administration, didn’t take into account that Moscow is the aggressor while Kiev is trying to regain sovereign territory. This week’s Russian escalation further discredits Minsk II, which was already a diplomatic fiction to most people outside the German Chancellery.

Mr. Putin is a master of strategic unpredictability, but he may be trying to consolidate his territorial gains in eastern Ukraine ahead of a “grand bargain” with Washington that could entail lifting Ukraine-related sanctions in return for Moscow’s cooperation in other areas, such as terrorism and nuclear disarmament.