The Indian government has called for Pakistan's ambassador to India to appear before its officials in New Delhi after one of Pakistan's navy ships had a clash with one of India's navy ships in the waters of the Arabian Sea. The Indian Ministry of External Affairs has said that the clash was an act of "unacceptable and unprofessional conduct," adding that it went against the terms of a 1991 treaty which requires the maintenance of three nautical miles distance between naval ships. This is the first case of military tension between the two nations since last year's four-day war.