The US has key military capabilities that are not replicated in European forces. These include considerable ISR assets, including signals intelligence collection, reconnaissance satellites and high-level C2. Without the participation of the US Air Force, Europe’s ability to suppress Russian air defences is very limited, as is its ability to defend against ballistic missiles. The US has strategic airlift and sealift assets that significantly outweigh European capabilities.
In their statements, Starmer and Macron seem to envisage that the US ‘backstop’ would deter any Russian attack on the international force. The US could do this by providing strategic intelligence to help identify and counter any threats. The US could also pledge to assist the force should it be attacked. Deterrence of a Russian attack would be greatly enhanced if this arrangement was publicised and supported by US forces deploying into the operational area. This could include the deployment of US land quick reaction forces, ships entering the Black Sea and US air patrols over the operational area.
A key ‘inconvenient truth’ is that any Russian attack on the deterrent force would involve the members of the force in combat against Russia. This would have profound implications, particularly if, as
Secretary of Defense Pete Hegseth has stated, the US did not allow NATO Article 5 to apply to forces from NATO members that deployed into Ukraine.
Many European countries could be unwilling to deploy without assurances that the US could provide in extremis military support.