(Adds detail from Russia's new naval doctrine. This content was produced in Russia, where the law restricts coverage of Russian military operations in Ukraine.)

ST PETERSBURG, Russia, July 31 (Reuters) - President Vladimir Putin on Sunday signed a new naval doctrine which cast the United States as Russia's main rival and set out Russia's global maritime ambitions for crucial areas such as the Arctic and in the Black Sea.

Speaking on Russia's Navy Day in the former imperial capital of St Petersburg founded by Tsar Peter the Great, Putin praised Peter for making Russia a great sea power and increasing the global standing of the Russian state.

After inspecting the navy, Putin made a short speech in which he promised that what he touted as Russia's unique Zircon hypersonic cruise missiles, cautioning that Russia had the military clout to defeat any potential aggressors.

Shortly before the speech, he signed a new 55-page naval doctrine, which sets out the broad strategic aims of Russia's navy, including its ambitions as a "great maritime power" which extend over the entire world.

The main threat to Russia, the doctrine says, is "the strategic policy of the USA to dominate the world's oceans" and the movement of the NATO military alliance closer towards Russia's borders.

Russia may use its military force appropriately to the situation in the world's oceans should other soft powers, such as diplomatic and economic tools, be exhausted, the doctrine says, acknowledging that Russia does not have enough navy bases globally.

Russia's priority was to develop strategic and naval cooperation with India as well as wider cooperation with Iran, Iraq, Saudi Arabia and other states in the region, according to the doctrine.

"Guided by this doctrine, the Russian Federation will firmly and resolutely defend its national interests in the world's oceans, and having sufficient maritime power will guarantee their security and protection," the document said.

Putin's speech did not mention the conflict in Ukraine, but the military doctrine envisages a "comprehensive strengthening of Russia's geopolitical position" in the Black and Azov seas.

Relations between Russia and the West have undergone deepening strain during the five months of the Ukraine conflict.

The doctrine also sets out the Arctic Ocean, which the United States has repeatedly said Russia is trying to militarise, as an area of particular importance for Russia.

Russia's vast 37,650 km (23,400 mile) coastline, which stretches from the Sea of Japan to the White Sea, also includes the Black Sea and the Caspian Sea.