US President Donald Trump has gone all in with his effort to strongarm Kyiv into peace negotiations with Russia, suspending US military aid to Ukraine with immediate effect.

Washington's suspension of military assistance will not lead to a sudden collapse of Ukraine's defensive lines, but it could have a real impact on the war within months, undermining air defences and precision strike capabilities in particular.

The United States is temporarily suspending all military aid to Ukraine, according to a senior administration official, who said the aid would not resume until President Trump determined that Ukraine had demonstrated a commitment to peace negotiations with Russia.