Cuba declared its independence from Spain in 1895, as part of a revolution led by Cuban nationalist Jose Marti. Many Cubans had desired independence from Spain for years, and in fact the revolution was the second in less than fifty years. But by the late nineteenth century, Cuba had also become a major economic interest of the United States, with sugar planters and other businessmen investing millions in plantations on the island. It is important to note that Marti and his sympathizers wanted political independence from Spain and economic independence from the United States, which was taking an increasingly imperialistic posture towards Cuba as the nineteenth century progressed. By declaring its independence, Cuba could forestall American attempts to take the island in the event of war with Spain. The revolutionary struggle became an opportunity for the United States to intervene in the region, and war began when a warship, the USS Maine, exploded in Havana harbor after being sent there ostensibly to protect American business interests. When the United States went to war, the Cuban declaration of independence was one diplomatic reason that Congress passed the so-called "Teller Amendment," which stated that the United States would not annex Cuba. After the war was over, however, the new Cuban government agreed to the "Platt Amendment" to their constitution. This allowed the United States to intervene in Cuban affairs when American interests were threatened.