A work crew was spotted relocating a 1,000-foot chain of wrecking-ball-sized buoys from the Mexican side of the Rio Grande to the U.S. side on Monday, a day ahead of a hearing in federal court over whether the installation—done at the behest of Republican Gov. Greg Abbott—is illegal. The development was documented in a new filing by the Department of Justice, which claimed it was yet another instance of “Texas’ ongoing and flagrant violations” of the Rivers and Harbors Act, which bars waterway construction without approval from the U.S. Army Corps of Engineers. Abbott did not seek a federal sign-off for the barrier, nor did he ask permission to move the buoys across the river, the department said. The governor said Monday the move had been made “out of an abundance of caution,” a remark that came after the DOJ produced evidence showing that nearly 80 percent of the barrier was on Mexico’s side of the river. Mexico complained repeatedly, arguing it was a violation of its sovereignty. At a Tuesday morning hearing, a federal judge in Austin is set to hear arguments over whether to issue an emergency injunction that could force Texas to disassemble the barrier.