Abe said he will defend them "at all costs."
The uninhabited islands are controlled by Japan but also claimed by China. Japan's nationalisation of the islands in September triggered violent protests across China, hurting Japanese companies there and the economy.
China has sent surveillance ships regularly to waters near the islands, and aircraft from the two sides have trailed each other, raising the risk of missteps that could trigger a clash.
Japan has recently launched diplomatic efforts to ease tensions, with China-friendly officials visiting Beijing for talks.