What did the British believe the Russians were interested in Iran and Afghanistan?

The British believed that the Russians were interested in Iran and Afghanistan primarily to expand their influence and secure access to warm-water ports, which were critical for trade and military strategy. This concern was part of the broader context of the "Great Game," where both empires sought to assert dominance in Central Asia. The British feared that Russian expansion into these regions could jeopardize British interests in India and threaten the stability of their colonial empire. Thus, they viewed Russian activities as a direct challenge to their geopolitical interests.