China is upping the pressure again, saying it will hold three days of military exercises and boost patrols in the South China Sea.

State-run media reported on Friday that one of the country’s largest patrol ships is on its way south, where it will enter the South China Sea for a round-trip patrol journey to Singapore. Meanwhile, the country’s military plans three days of exercises in the sea, where Vietnam also recently conducted live-fire drills. China has raised hackles of both Vietnam and the Philippines this spring with what those countries say is aggressive behavior in their territorial waters. In all, six countries have disputed claims in the South China Sea and China is by far the largest and currently most aggressive.