President Trump is undermining his peace initiative with North Korea by abruptly raising the cost to South Korea for U.S. security.

Donald Trump and Vladimir Putin could take fresh approaches on contentious issues, including Russia’s meddling in U.S. elections, Ukraine, Syria, and arms control, to their meeting in Helsinki.

The Trump administration has made bold gestures in support of Taiwan, including more frequent movement of U.S. ships in the Taiwan Strait. They come at a time of growing anxiety about the U.S.-China …