Worried that strikes to Russia’s missile early warning system used to detect nuclear attacks could unsettle the Kremlin, the Biden Administration insisting on limits for Ukrainian forces using American weaponry, the Washington Post reports.  The caution came after Kyiv targeted a radar site 1,100 miles inside Russia.

The concern cuts in several ways.  Eliminating the advanced warning system allows Ukraine to more effectively strike targets in both Russia and Ukraine.  But the systems are also key to Russia’s nuclear deterrence capability against potential enemies like the United States and China.  Targeting these systems may push Moscow to higher alert and incite them to take more aggressive action including using nuclear weapons against Ukraine, administration officials fear.

“Russia could think it has a diminished ability to detect early nuclear activity against it, which then could become an issue,” a US official commented. “It should be obvious to everyone that there’s no [American] intention whatsoever of using nuclear weapons against Russia. But there’s certainly concern about how Russia could perceive its deterrent capabilities being targeted and early-warning systems being attacked.”

But the class of weapons identified by Washington are also used by Russia for offensive purposes, locating and targeting rocket, missile and artillery sites, which means they are a legitimate target for Ukraine.  With Biden reportedly ready to authorize the sale of US weapons that could strike deep into Russia, Ukraine wants to eliminate a key Russian asset, but Washington doesn’t want a Ukrainian strike to unsettle an already violent Russian regime.