Bhutan maintains strong economic, strategic, and military relations with India. In February 2007, the Indo-Bhutan Friendship Treaty was substantially revised, clarifying Bhutan's full control of its foreign relations, as well as its independance and sovereignty. Whereas the Treaty of 1949, Article 2 stated: "The Government of India undertakes to exercise no interference in the internal administration of Bhutan. On its part the Government of Bhutan agrees to be guided by the advice of the Government of India in regard to its external relations," the revised treaty now states "In keeping with the abiding ties of close friendship and cooperation between Bhutan and India, the Government of the Kingdom of Bhutan and the Government of the Republic of India shall cooperate closely with each other on issues relating to their national interests. Neither government shall allow the use of its territory for activities harmful to the national security and interest of the other." The revised treaty also includes this preamble: "Reaffirming their respect for each other's independence, sovereignty and territorial integrity", an element absent in the earlier version. By long-standing agreement, Indian and Bhutanese citizens may travel to each other's countries without a passport or visa, but must still have their national identity cards. Bhutanese citizens may also work in India without legal restriction.