ABOARD A U.S. MILITARY PLANE OVER THE PACIFIC — Less than a week after helping secure billions of dollars in additional military assistance for Ukraine in its fight against Russia, including U.S.- and German-made battle tanks, top U.S. defense officials are shifting their focus to the Indo-Pacific and growing threats from China and North Korea. Defense Secretary Lloyd Austin is making his sixth official visit to the region, starting late Monday with high-level meetings in Seoul, followed by a visit to the Philippines to meet with recently elected President Ferdinand Marcos, Jr. and his new national security leadership team. “The...