Indians are not stupid to put 1 million troops in Kashmir only to be easily taken out. Our commands are spread by different areas of the country. At most we'll have 40,000-70,000 troops in Kashmir.
In any case, if Pakistan did cut off our troops from the rest of Indian then our Navy will be easily able to ensure a Naval blockade on your western sector. We may be lacking in terms of equipment for army or airforce but our Navy has done exceptionally well in terms of building our capability. We're stronger than ever.