By JOSH LEDERMAN, Associated Press

WASHINGTON (AP) — The top American and North Korean diplomats may cross paths during a regional summit next week in the Philippines, but have no plans to meet, the United States said Wednesday as it sought to further isolate the North over its nuclear weapons program.

Secretary of State Rex Tillerson and North Korean Foreign Minister Ri Yong Ho are both attending a Southeast Asia summit that is expected to focus heavily on regional concerns about the North. Susan Thornton, the top Asia hand in the State Department, said Tillerson had no plans to sit down with Ri.

"I don't expect to see that happen," Thornton told reporters ahead of Tillerson's trip. "What we would expect to see this year at the meeting would be a general chorus of condemnation of North Korea's provocative behavior, and a pretty serious diplomatic isolation directed at the North Korean foreign minister."

Tillerson's reluctance to sit down with his North Korean counterpart comes despite his growing push for Pyongyang to return to the negotiating table with the U.S. Tillerson said this week that such talks would have to be predicated on the North giving up its nuclear weapons aspirations and that the conditions for such talks haven't yet been met by North Korea's government.

In the meantime, the U.S. sought to up the economic pressure on North Korea by urging countries that do business with it to stop, or at least to seriously curtail trade. And the U.S. and allied militaries have been conducting a series of exercises and tests to demonstrate their ability to counter Pyongyang's weapons capabilities.

Across the Pacific Ocean from North Korea, in California, the U.S. Air Force said a test Wednesday of an unarmed intercontinental ballistic missile was successful. It was the fourth test this year and involved a Minuteman 3 missile, regularly launched across the Pacific by the U.S. in a display of its effectiveness, readiness, and accuracy.

In another sign of U.S. concern about the North, the Trump administration issued an updated traveling warning Wednesday urging Americans currently there to leave before a new travel ban takes effect on Sept. 1. The Trump administration announced that ban last month over concerns about detention of Americans who travel to the North.

The ban, which includes potential exceptions for journalists and humanitarian workers, expires one year later unless extended by Tillerson. The State Department said exceptions will only be granted under "very limited circumstances" and that it doesn't yet know when it will release information about how to apply.

Tillerson likely will meet while in Asia with China's foreign minister, Thornton said, just as the U.S. presses Beijing to isolate North Korea by reducing its economic and other ties. After traveling to Manila for the summit, Tillerson will head to Thailand and to Malaysia for brief stops in which North Korea concerns are likely to be a prime focus as well.

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Reach Josh Lederman on Twitter at http://twitter.com/joshledermanAP