WASHINGTON — When President Trump made the surprise announcement in March that he would soon meet with the North Korean leader, Kim Jong-un, Secretary of State Rex W. Tillerson was thousands of miles away, an absence interpreted as a sign of Mr. Tillerson’s irrelevance.
Mr. Trump soon replaced Mr. Tillerson with Mike Pompeo, who has promised to bring back the State Department’s “swagger” and import. But on Tuesday, when Mr. Trump made what could be the most significant diplomatic announcement of his presidency — that he would exit the Iran nuclear agreement — his chief diplomat was again thousands of miles away, this time on an unannounced visit to Pyongyang, the North’s capital, to lay further groundwork for a summit meeting between Mr. Kim and Mr. Trump.
The absence of Mr. Pompeo and other top State Department officials left perplexed European diplomats privately complaining that they were having trouble getting answers from Washington, and created an uncertainty about what was next that spanned the Atlantic Ocean.
Senior State Department officials were momentarily speechless Tuesday when asked why Mr. Pompeo did not delay his trip by a day to be in Washington during Mr. Trump’s Iran deal announcement. Mr. Pompeo left for Pyongyang on Monday night.
One official cited the separate nature of the two sets of negotiations. Another said Mr. Pompeo had remained reachable, citing the plane’s communications system. But the secretary’s aging plane has such poor equipment that calls are often dropped midsentence.
Brian Hook, who led negotiations with the Europeans for a supplemental agreement to the Iran deal, was also on the plane to Pyongyang on Tuesday, worsening the communications problems.
The senior State Department officials who briefed reporters in the moments after Mr. Trump’s announcement confirmed that they did not know whether European countries would fight the administration’s plan to reimpose sanctions on Iran, a crucial test of whether the administration’s strategy would work. Nor does the administration know whether European countries will agree to try to negotiate a new agreement with Iran or whether a tentative deal the two sides created to address Iran’s ballistic missile program would go into effect, the officials said.
One of the officials said American and European officials had not discussed a Plan B. Those discussions were beginning Tuesday, the official said, although neither Mr. Pompeo nor Mr. Hook was in Washington or any European capital to begin them.
Meanwhile, Mr. Pompeo told reporters on his plane that his agenda in North Korea was to reach agreement on the date, time and specific location for the summit meeting between Mr. Kim and Mr. Trump.
“And the location is important. But there are many conditions that play into that. How long is it going to go on? When you say where, like really where? Not just a city or a country, but like really where?” Mr. Pompeo said. “So we’re trying to put some more meat on that.”
Mr. Pompeo is widely expected to leave Pyongyang with three Americans now imprisoned in North Korea. All of them are Korean-Americans and all have the surname Kim, although they are not related.
Asked whether he expected the North Koreans to release the three detainees to him, Mr. Pompeo said, “I think it’d be a great gesture if they would choose to do so.” And asked whether a summit meeting was possible if the North Koreans continued to detain the Americans, he said, “We’re hopeful we don’t have to cross that road.”
Mr. Pompeo also stressed, as he has done on almost every occasion when publicly speaking about the summit meeting between Mr. Trump and Mr. Kim, that the United States would not support a proposal by President Moon Jae-in of South Korea for step-by-step measures, in which the North Koreans would get sanctions lifted over a period of years as they gradually unwound their nuclear program.
“We’re not going to relieve sanctions until such time as we achieved our objectives,” he said. “We are not going to do this in small increments, where the world is essentially coerced into relieving economic pressure.”
Many analysts in South Korea and around the world believe that such an all-or-nothing strategy will fail with the North Koreans, but a senior administration official traveling with Mr. Pompeo pointed out that previous administrations had tried incremental measures, all of which failed to halt the country’s progress toward building a nuclear arsenal and the missiles to deliver them.
The senior official said that Mr. Kim promised as recently as New Year’s Eve that the country would mass produce nuclear warheads and the means to deliver them, and that a year ago he had ordered the assassination of his half brother with the use of a chemical weapon. One goal of the trip, the official said, was to see whether the North was ready to take the steps needed to prove it had moved beyond such talk and actions.