LONDON, March 5 (Reuters) - British Prime Minister Keir Starmer said on Thursday that four additional Typhoon fighter jets would be sent to Qatar as the conflict in the Middle East escalates, insisting that the UK has the right plan for defence. Britain's cautious response to the Iran crisis and a drone attack on its key military base in Cyprus have led to doubts among partners about its military effectiveness. U.S. President Donald Trump has also criticised Starmer for failing to provide suffic...