Artificial islands as conquest by civil engineering

Are China's artificial islands in the South China Sea a presence mission, more like Hadrian's Wall than the Great Wall of China?

Yes. They amount to conquest by civil engineering, creating forward positions that other forces must take into account.

The artificial islands function as a presence mission in the South China Sea. The phrase "conquest by civil engineering" captures how construction can change the strategic situation without a conventional amphibious seizure. They resemble Hadrian's Wall more than the Great Wall of China: forward positions that assert and sustain control rather than an impermeable barrier. Their practical importance is that every other force operating in the area must now plan around installations that physically exist in the disputed waters.