The Kori Creek (, ) is a tidal creek and maritime Border dispute  between the Kutch region of the Indian state of Gujarat and the Kachchhi region of the Pakistani province of Sindh. It is in the Rann of Kutch marshland east of the Sir Creek, which is disputed between India and Pakistan. It is a 96 km (60 mi) strip of water disputed between the Republic of India and Pakistan, claimed by India as a part of the Indian Rann of Kutch marshlands. The creek, which opens up into the Arabian Sea, divides the Kutch region of the Indian state of Gujarat with the Sindh province of Pakistan. 
The long-standing dispute hinges in the actual demarcation "from the mouth of Kori Creek to the top of Kori Creek, and from the top of Kori Creek eastward to a point on the line designated on the Western Terminus". From this point onwards, the boundary is unambiguously fixed as defined by the Tribunal Award of 1968.

The creek itself is in the uninhabited marshlands. During the monsoon season between June and September, the creek floods its banks and envelops the low-lying salty mudflats around it. During the winter season, the area is home to flamingoes and other migratory birds.

Dispute

The dispute is in the interpretation of the boundary line between Kutch and Sindh as depicted in a 1914 and 1925 map. At that time, the region was a part of Bombay Presidency of undivided India. After India's independence in 1947, Sindh became a part of Pakistan while Kutch became a part of India.

The resolution, which demarcated the boundaries between the two territories, included the creek as part of Sindh province, thus setting the boundary as the eastern flank of the creek. The boundary line, known as the "Green Line", is disputed by India which maintains that it is an indicative line, known as a "ribbon line" in technical jargon. India's position is that the boundary is mid-channel as depicted in another map drawn in 1925, and implemented by the installation of mid-channel pillars back in 1924.

India supports its stance by citing the Thalweg Doctrine in International Law. The law states that river boundaries between two states may be, if the two states agree, divided by the mid-channel. Though Pakistan does not dispute the 1925 map, it maintains that the Doctrine is not applicable in this case as it only applies to bodies of water that are navigable, which the Kori Creek is not. India rejects the Pakistani stance by maintaining the fact that the creek is navigable in high tide, and that fishing trawlers use it to go out to sea. Several cartographic surveys conducted have supported the Indian claim. Another point of concern for Pakistan is that Kori Creek has changed its course considerably over the years. If the boundary line is demarcated (outlined) according to the Thalweg principle, Pakistan stands to lose a considerable portion of the territory that was historically part of the province of Sindh. Accepting India's stance would also result in the shifting of the land/sea terminus (end) point several kilometres to the disadvantage of Pakistan, leading in turn to a loss of several thousand square kilometres of its Exclusive Economic Zone under the United Nations Convention on Law of the Sea.

In April 1965, a dispute there contributed to the Indo-Pakistani War of 1965, when fighting broke out between India and Pakistan. Later the same year, British Prime Minister Harold Wilson persuaded both countries to set up a tribunal to resolve the dispute. A verdict was reached in 1968, which saw Pakistan getting 10% of its claim of 9,000 km² (3,500 sq. miles).

The disputed region was at the center of international attention in 1999 after Mig-21 fighter planes of the Indian Air Force shot down a Pakistani Navy Breguet Atlantique surveillance aircraft over the Kori Creek on August 10, 1999, killing all 16 on board. India claimed that the plane had strayed into its airspace, which was disputed by the Pakistani navy. (See the Atlantique Incident)

Economic reasons
Though the Kori Creek has little military value, it holds immense economic gain. Much of the region is rich in oil and gas below the sea bed, and control over the creek would have a huge bearing on the energy potential of each nation. Also once the boundaries are defined, it would help in the determination of the maritime boundaries which are drawn as an extension of onshore reference points. Maritime boundaries also help in determining the limits of Exclusive Economic Zones (EEZs) and continental shelves. EEZs extend to 200 nautical miles (370 km) and can be subjected to commercial exploitation.

The demarcation would also prevent the inadvertent crossing over of fishermen of both nations into each others' territories.

Dispute resolution
The Federal Government of Pakistan lays claim to the entire creek as per paras 9 and 10 of the Bombay Government Resolution of 1914 signed between the then provincial Government of Sindh and Rao Maharaj, then the ruler of the former Princely state of Kutch.
However since 1969, there have been eight rounds of talks between the two nations, without a breakthrough. Steps to resolve the dispute include:
 Allocation
 Delimitation
 Demarcation
 Administration

Since neither side has conceded ground, India has proposed that the maritime boundary could be demarcated first, as per the provisions of Technical Aspects of Law of Sea (TALOS). However, Pakistan has firmly refused the proposal on the grounds that the dispute should be resolved first. Pakistan has also proposed that the two sides go in for international arbitration, which India has flatly refused. India maintains that all bilateral disputes should be resolved without the intervention of third-parties.

References 

Rivers of Pakistan
Territorial disputes of India
Territorial disputes of Pakistan