WASHINGTON >> The meeting between acting Defense Secretary Patrick Shanahan and his Chinese counterpart began with all the hallmarks of a routine staged and scripted session between two uneasy rivals.

First came the posed photo, as the two men shook hands with broad smiles in front of their nations’ flags, and then they moved quickly into the hotel conference room, surrounded by staff. There, Shanahan presented Chinese Defense Minister Wei Fenghe with a gift.

But what at first glance looked like a coffee table book was actually 32 pages of photographs and satellite images of North Korean ships getting and delivering shipments of oil. Many of the photos are stamped with dates, times, locations and descriptions, and, according to officials, represent proof that Pyongyang is violating punishing economic sanctions right off China’s coast.

“I gave him this beautiful book,” Shanahan said a day after his meeting with Wei and his top staff at a national security conference in Singapore. “I said this is an area where you and I can cooperate.”

The pointed message from the acting Pentagon chief comes as the Trump administration is at odds with China over a wide range of issues, including trade, Chinese theft of American technology, the possible sale of U.S. weapons to Taiwan and how to pressure North Korea into giving up its nuclear weapons program.

China agreed to the U.N. sanctions against its ally and neighbor North Korea, but, as the photo book illustrates, appears to be allowing violations to take place.

On one page of the book viewed by The Associated Press, a photo shows the North Korean-flagged oil tanker Kum Un San 3 next to the M/V New Regent, a Panama-flagged tanker, and a number of lines and hoses are draped between the two ships. The photo is dated June 7, 2018.

The U.N., in an October 2018 press release, said the June 7 ship-to-ship transfer was a violation and said it likely involved oil. The U.N. sanctioned the two ships and said they are subject to de-flagging and prohibited from entering U.N. member ports.

Another photo in the book shows the North Korean tanker An San 1, and says it is “offloading refined petroleum” through an undersea pipeline at the terminal in Nampo, near Pyongyang.

Lt. Col. Joe Buccino, a Pentagon spokesman, said Shanahan devised the book to show that enforcement of U.N. sanctions off the Chinese coast is “an area for potential coordination and collaboration” with the Chinese military.

A U.S. defense official said Shanahan had the photographs and information in the book declassified and bound. Shanahan presented the book to Wei at the start of their meeting, saying he had a gift for the minister, said the official, who spoke on condition of anonymity to discuss a private meeting. The official said Wei initially appeared taken aback at receiving a gift, but when he realized what it was he quickly turned it over to his staff.

During the meeting, Shanahan told Wei that the U.S. and Chinese navies could work together to prevent such violations of the U.N. sanctions, said the official.

“It’s actually very clever,” said Bonnie Glaser, director of the China power project at the Washington-based Center for Strategic and International Studies. “It’s really calling out China. This is a way of telling them that we know what’s going on, we have quite a bit of evidence, and here’s an opportunity for you to expand cooperation with the United States.”

Glaser, who also attended the Singapore conference, said she spoke with members of the China delegation and they described the meeting between Shanahan and Wei as positive and upbeat. No one, she said, mentioned the book.

“I think it was probably embarrassing,” she said. “They probably thought they were getting something wonderful, that would highlight something positive, not something calling out China for their failure to step up and crack down on North Korea.”

The oil and trade sanctions against North Korea have hurt its already struggling economy, and both Russia and China have called for easing them. China isn’t likely to want to openly evade the sanctions and face diplomatic friction with the United States, but more than 90% of North Korea’s foreign trade has gone through China.

The U.N. Security Council in March said North Korea was continuing to defy its resolutions through a “massive” increase in ship-to-ship transfers of petroleum products and coal. The U.S. Navy has been working with a number of countries, including South Korea, Japan, Australia, New Zealand, Canada and France, to catch sanctions violations such as ship-to-ship transfers.

Shanahan’s meeting with Wei at the Shangri-La Dialogue security conference earlier this month came just the evening before he delivered a speech that denounced China’s efforts to steal technology from other nations and militarize man-made outposts in the South China Sea as a “toolkit of coercion.” But he also made clear the U.S. wants to work with China on other international issues.

In a brief mention of the book during questions after his conference speech, Shanahan said the two countries must work through their differences.

“Trust is built over time,” he said. “Trust is built by working on projects and being shoulder to shoulder. It isn’t done by conferences or by policies or by speeches. We need to find areas in which we can grow.”