Background:
During the early years of Indian independence, the Nehru cabinet faced various challenges, including border disputes with neighboring countries. One such major challenge was the apprehension of a future attack from China. Among the members of the Nehru cabinet, Vallabhbhai Patel was particularly concerned about this threat.

Explanation:
Vallabhbhai Patel's Concerns:
1. Understanding China's Expansionist Policies: Vallabhbhai Patel had a deep understanding of China's expansionist policies and their aggressive stance towards territorial claims. He was aware of China's annexation of Tibet in 1950 and their claims on territories in India's northeastern region.
2. Border Disputes: Patel was also well-informed about the border disputes between India and China, especially in areas like Aksai Chin and the McMahon Line. He realized the strategic importance of these regions and the potential for conflict.
3. Intelligence Reports: Patel had access to intelligence reports that indicated China's increasing military presence along the border with India. These reports highlighted the vulnerability of India in the face of a possible attack.
4. Military Infrastructure: Patel was concerned about India's inadequate military infrastructure along the northern border, which made the country more susceptible to Chinese aggression.
5. Lack of Preparedness: Patel felt that India was not adequately prepared to defend itself against a potential Chinese invasion, given the prevailing political, economic, and military conditions. He believed that urgent measures were required to strengthen India's defenses.

Conclusion:
Vallabhbhai Patel's apprehension of a future attack from China stemmed from his understanding of China's expansionist policies, border disputes, intelligence reports, the lack of military infrastructure, and India's overall unpreparedness. His concerns were justified, as India indeed faced a military conflict with China in 1962, known as the Sino-Indian War. Patel's foresight regarding the Chinese threat highlights his strategic thinking and the importance he placed on national security.