WASHINGTON >> Two shipping containers full of hygiene kits languish for weeks in a Chinese port, unable to reach North Korea. They’re intended for people with tuberculosis or hepatitis, not to advance nuclear or missile programs, but Chinese customs officers see something objectionable in the cargo: nail clippers.

As sanctions on Kim Jong Un’s government intensify, the few aid groups operating in North Korea are facing sometimes bewildering economic restrictions and bureaucratic hurdles that could cripple life-saving work. While the U.N. Security Council says the penalties shouldn’t affect humanitarian help, the Trump administration cites even North Korea’s reported food and fuel shortages as evidence of a pressure campaign working.

The nail clippers were part of a consignment sent by Christian Friends of Korea, among the U.S. charities working in North Korea despite escalating nuclear tensions. The latest round of U.N. sanctions bans the supply of metal items, so that explains the clipper holdup.

It’s not the only example. The American Friends Services Committee, another aid group, is struggling to deliver agricultural equipment such as threshers, compost makers and shovels.

“Sanctions should not have an impact on the well-being of ordinary citizens,” said Linda Lewis, a member of the Quaker committee that’s helped North Korean farmers for two decades. “This work should not be shut down for political reasons.”

How do you pressure governments, short of war, to change their behavior without unduly injuring innocent civilians?

That’s one of biggest questions for the economists, foreign policy professionals and political leaders who devise and put in place economic sanctions around the world. U.N. penalties routinely include broad exceptions for most basic civilian goods. Even when the United States targets its most intractable foes, it exempts food, medicine and humanitarian supplies.

In the case of North Korea, which the U.S. and others want to rid of nuclear weapons, it’s unclear whether the right balance is being struck.

Citing reports last week from Tokyo of scores of North Korean fishing boats, with dead crews, drifting into Japanese waters, Secretary of State Rex Tillerson said the sanctions are “really starting to hurt.” The human suffering, he said, was North Korea’s responsibility and an “unavoidable outcome” of its failure to help its own people.

Tillerson also doubted that humanitarian assistance, which South Korea is considering, would reach the right people in the North.

His remarks alarmed humanitarian advocates. But given that the alternative to the U.S.-led pressure may be military conflict, the Trump administration is getting much leeway from international partners and the public over how the sanctions are affecting North Korea’s 25 million people. Recent visitors to the isolated country say fuel prices have risen, but food supplies don’t seem any scarcer. They anticipate conditions to worsen in the coming months.

Three times in the past year, the U.N. Security Council has tightened economic restrictions on North Korea, cutting fuel supplies and banning trade in the goods that make up 90 percent of the North’s export revenue. The latest round, designed to punish a North Korean long-range missile test, prohibit selling the North iron, steel and other metals. That covers nearly 150 different categories of products, covering everything from stainless steel ingots to spoons and paper clips.

For U.S. aid groups, tiny operations already hindered by myriad requirements from U.S. authorities, the new rules are causing headaches. The groups need special export licenses from the departments of Commerce or Treasury; special U.S. customs inspections of their cargo; and State Department waivers to travel to North Korea. They also must contend with reluctant banks and suppliers, fearful of being fined for any transaction related to North Korea.

In the case of the nail clippers, Heidi Linton of the Christian Friends of Korea, which supports more than 30 tuberculosis and hepatitis care centers, said its routine shipment of hygiene kits was stuck this month in the northern Chinese port of Dalian for two weeks. Finally, Chinese customs gave special permission for the shipment to proceed. Without that decision, Linton would have had to pay people to individually unpack the metal nail clippers from several thousand kits for the two containers to be cleared.

“To what purpose?” asked a relieved and grateful Linton, who now wonders whether her group can import a replacement clutch for its vehicle in North Korea. It needs other metal items for renovating clinics and for clean water projects.

Lewis, from the Quaker aid group, echoed the sentiment.

“Now we can’t even send shovels, anything made of steel,” she said. Her group helps four cooperative farms in North Korea and had no problem with shipping basic agricultural equipment just a few months ago.

Lewis joked that the specific prohibition covering shovels must be an “excessively conservative interpretation” of dual-use technologies that are targeted in U.N. sanctions because they can have both peaceful civilian and lethal military uses. It’s unclear what specific military use a shovel has.

For North Korea’s civilians, the aid groups play a crucial role. The U.N. works on child health care and provided food for more than 800,000 North Koreans last year. “Sanctions may be adversely affecting that essential help,” U.N. human rights chief Zeid Ra’ad al-Hussein told the Security Council last month.

The country is in far better shape than the famine years of the 1990s, when hundreds of thousands starved to death. But 70 percent of the people still suffer food insecurity, and 2 in 5 are undernourished, according to the U.N. The aid group Care International calls it the world’s most under-reported humanitarian crisis.

Most governments refuse to help.

The U.S. last gave aid to North Korea a decade ago. Few others are stepping up when North Korea’s Kim is being almost universally lambasted for plowing his impoverished nation’s sparse resources into weapons.

The United Nations’ $114 million humanitarian appeal last year, mostly for children and mothers, was only 30 percent funded. In November, the World Food Program was compelled by a money shortage to exclude 190,000 children from a program that offers cereal and enriched biscuits to the hungry.

China had long resisted the U.S. pressure to use all its economic leverage on North Korea. It’s unclear why authorities are now interpreting the rules so strictly. The U.N. resolutions on North Korea specify they’re “not intended to have adverse humanitarian consequences.”

Chinese Foreign Ministry spokeswoman Hua Chunying acknowledged the problems with humanitarian aid resulting from the North Korea sanctions, but said her country “always completely and strictly implements Security Council resolutions.”