Explanation:
A landlocked country is a country that has no direct access to the open sea or ocean.
The 12 landlocked countries in Asia are Afghanistan, Armenia, Azerbaijan (bordered by the Caspian Sea, which is an inland sea and does not provide access to the world's oceans), Bhutan, Kazakhstan (Caspian Sea is an inland sea), Kyrgyzstan, Laos, Mongolia, Nepal, Tajikistan, Turkmenistan (Caspian Sea coast only), Uzbekistan.
Also note, Uzbekistan is one of only two doubly landlocked countries in the world (the other is Liechtenstein), meaning every neighboring country is also landlocked.