And the sanctions may not prove effective. The North has learned through decades of US efforts at isolation how to circumvent commercial and financial restrictions, and reluctant powers like China and Russia have often proven half-hearted partners when it comes to policing their ally.

"On paper, this is a pretty strict containment of North Korea economically," said Scott Snyder, an expert on Korea at the Council on Foreign Relations. "But North Korea has been able to evade sanctions in the past and it's not clear to me things are going to be much different this time."


Speaking in the Philippines after meeting Asian foreign ministers, Secretary of State Rex Tillerson on Monday said there is "no daylight" in the view among Washington and its partners that North Korea must move toward abandoning its nuclear weapons. But he was quick to stress the importance of everyone enforcing the new, tougher sanctions.

"We will be monitoring that carefully," he said.

The UN penalties aim to cut off roughly $1 billion of North Korea’s estimated $3 billion in annual exports, by banning countries from importing its coal, iron, lead and seafood products, and stopping them from letting in more North Korean laborers, who help Kim's government by sending cash home. President Donald Trump’s UN ambassador, Nikki Haley, called it "the single largest economic sanctions package ever leveled against" North Korea.

Even if, in the best-case scenario, the sanctions hurt North Korea's economy and weaken its government, questions remain over what to do next. Can North Korea be persuaded to give up its weapons of mass destruction, removing the threat to the United States and its allies, South Korea and Japan? If not, what new options does the United States have? Trump is only the latest US president to choose sanctions instead of confronting the North militarily or offering diplomatic talks without nuclear concessions.

Much rests on the willingness of China, the North’s traditionally ally and main trading partner. China opposes Pyongyang's nuclear weapons, and was uncharacteristically forthright in saying so this week. But it remains cautious of triggering a North Korean collapse, fearful of fomenting chaos along its border or advancing any scenario that would lead to a reunified and US-allied Korea on its doorstep.

Anthony Ruggiero, a former Treasury Department official and sanctions expert, said China and Russia have failed to implement a half-dozen previous UN resolutions on North Korea since 2006, when the country became the first and only one this century to conduct a nuclear test explosion. Four further atomic tests since then have honed its capability to miniaturize a nuclear device. Last month’s pair of groundbreaking tests of long-range ballistic missiles has put the continental United States in range for the first time.

While uncertainty remains over the North's ability to wed a warhead with such a missile and strike a US target, it is a prospect that looms larger over Trump’s presidency.

As a matter of urgency, Ruggiero argued, the US should punish Chinese banks and companies helping North Korea evade sanctions. Any such action may now face delays, as Washington will first have to gauge Beijing's implementation of the new penalties.

Amid all the pressure, the Trump administration has left open the possibility of resuming talks with Pyongyang.

In Manila, Tillerson said he hoped the North would "choose a different pathway and when the conditions are right, that we can sit and have a dialogue." He urged North Korea to first halt tests for an "extended period," however often such confidence-building measures have failed.

North Korean shows scant interest in playing by America’s rules. Foreign Minister Ri Yong-ho told Asian foreign ministers at the same meeting Tillerson attended that "under no circumstances" will his country put its nuclear weapons or ballistic missiles on the negotiating table.

Without such a commitment, talks appear unlikely.

Washington has dismissed a Chinese proposal designed to pique Pyongyang's interest: a suspension of American military exercises with South Korea if the North freezes its weapons development.

The stances reflect a fundamental impasse that no amount of sanctions may be able to change. While the US position is that North Korea must ultimately give up its nukes, the North insists it must keep them.

Richard Nephew, a former State Department official who helped craft the 2015 nuclear deal with Iran, wrote that for sanctions to succeed, they have to be paired with a credible negotiating effort.

It’s time to "cut a deal," Nephew wrote on the 38 North website, "to reduce the threat of North Korea's existing arsenal and to stabilize the peninsula before the situation gets out of hand." (AP)