Complex sentence: This led to an abortive US operation to control of the city in Operation Vigilant Resolve or what is known as First Battle of Fallujah, the armed groups had increased their attacks on the American forces throughout the siege on Fallujah.
Split into simpler sentences: This led to an abortive US operation to control of the city in Operation Vigilant Resolve or what is known as First Battle of Fallujah. Armed groups increased their attacks on the American forces throughout the siege on Fallujah.