to be settled with Indonesia over the overlapping claims on the Ambalat continental shelf in the Celebes Sea and land border dispute between Sabah and North Kalimantan. Malaysia's claim over a portion of the Spratly Islands is also based on sharing a continental shelf with Sabah. The Philippines has a territorial claim over much of the eastern part of Sabah. It claims that the territory is connected with the Sultanate of Sulu and was only leased to the North Borneo Chartered Company in 1878 with the Sultanate's sovereignty never being relinquished. Malaysia however, considers this dispute as a "non-issue", as it interprets the 1878 agreement as that of cession and that it deems that the residents of Sabah had exercised their right to self-determination when they joined to form the Malaysian federation in 1963. The Philippine claim can be originated based on three historical events; such as the Brunei Civil War from 1660 until 1673, treaty between Dutch East Indies and the Bulungan Sultanate in 1850 and treaty between Sultan Jamal ul-Azam with Overbeck in 1878. Further attempts by several Filipino politicians such as Ferdinand Marcos to "destabilise" Sabah proved to be futile and led to the Jabidah massacre in Corregidor Island, Philippines. As a consequence, this led the Malaysian government to once supporting the insurgency in southern Philippines. Although the Philippine claim to Sabah has not been actively pursued for some years, some Filipino politicians have promised to bring it up again, while the Malaysian government have asked the Philippines not to threaten ties over such issue. To further discourage pursuit of the claim the Malaysian government passed a barter trade ban, at the behest of the Royal Malaysia Police and the Malaysian Deputy Prime Minister, between Malaysia and the Philippines as it was seen to only benefit one side while threatening the security of the state. The ban was positively received by many Sabahans, although there was opposition from other political parties as well as from the residents of neighbouring Philippine islands due to a sharp rise in living costs after the ban took effect. Barter trade activity was resumed on 1 February 2017 upon the agreement by both Malaysian and the Philippine authorities to fortify their respective borders with increased surveillance and security enforcement. Despite the return of barter trade activity, the state of Sabah maintained that they will remain vigilant in trading with the Philippines. In