As Putin heads for North Korea, South fires warning shots at North Korean soldiers who temporarily crossed border

Seoul, South Korea — Russian President Vladimir Putin thanked North Korea for supporting his actions in Ukraine and said their countries will cooperate closely to overcome U.S.-led sanctions as he headed to Pyongyang on Tuesday for a summit with North Korean leader Kim Jong Un.

Putin's visit comes as tensions on the Korean Peninsula hit their highest point in years, with the pace of both Kim's weapons tests and the combined military exercises between the United States, South Korea and Japan intensifying in a cycle of tit-for-tat. The Koreas have also engaged in a Cold War-style psychological warfare that involved North Korea dropping tons of trash on the South with balloons and the South broadcasting anti-Korean propaganda broadcasts with its loudspeakers.

South Korea's military said soldiers fired warning shots to repel North Korean soldiers who temporarily crossed the rivals' land border Tuesday for the second time this month. The South's military said North Korea has been increasing construction activity in frontline border areas, such as installing suspected anti-tank barriers, reinforcing roads and planting landmines.