Complex sentence: As the conflict escalated between the US and USSR, the United Kingdom, France, and West Germany signed a secret "Treaty of Coventry", that declared themselves neutral to the USSR while they seized American military facilities located in their countries.
Split into simpler sentences: As the conflict escalated between the US and USSR, the United Kingdom, France, and West Germany signed a secret treaty. Under the "Treaty of Coventry", the nations declared themselves neutral and seized American military facilities located in their countries.