Pyongyang, with its ruthless leader and laser focus on attaining nuclear weapons that can strike the US, is arguably the toughest foreign policy challenge facing the Trump administration.

North Korea scares the region and has stymied past US presidents. Trump administration officials have warned that "all options are on the table" for responding to Pyongyang. It's fair to say none of them are good, but what they?

1. Economic pressure

The US and United Nations have introduced sanctions that make it hard for North Korea to use the international financial system or for its businesses to function abroad. But they haven't changed Pyongyang's trajectory.

Now, Secretary of State Rex Tillerson has put countries on notice that if they or their companies help North Korea -- also known as the DPRK -- they'll face penalties. That mostly means China, which accounts for 90% of North Korea's trade.

That doesn't seem to be working yet.

Trade between China and North Korea grew almost 40% in the first quarter. So much for China working with us - but we had to give it a try! — Donald J. Trump (@realDonaldTrump) July 5, 2017

North Korea has been accused of funding its missile program through illicit dealings across the globe -- with crimes such as hacking banks, selling weapons, dealing drugs, counterfeiting cash and even trafficking endangered species.

These operations are believed to rake in hundreds of millions of dollars and allow Pyongyang to pursue its nuclear ambitions as sanctions cripple the country's economy, according to analysts who spoke to CNN.

Experts say shutting off that revenue may prove difficult, like playing a game of international whack-a-mole, due to North Korea's adaptive overseas network used to nest and disguise their illicit business amongst legal trade activities.

2. Cyber and information wars

This could involve penetrating North Korea with news about the outside world, to undermine the regime's control. Another approach would be cyber attacks to disrupt Pyongyang's weapons programs -- though experts say that would only delay, rather than stop them.

3. Diplomatic dialogue

Previous US administrations have tried dialogue -- past talks have included South Korea, Japan, China and Russia. They haven't worked. For 20 years, North Korea has promised to drop its nuclear program in exchange for aid and sanctions relief -- and then broken those promises.

Earlier this year, Trump said he would be willing to meet with North Korean leader Kim Jong Un "under the right circumstances" to defuse tensions over North Korea's nuclear program.

No sitting US president has ever met with the leader of North Korea while in power, and the idea is extremely controversial, but some lawmakers have said they would be willing to support the idea following Pyongyang's latest missile test.

4. An international pressure campaign

This is new, and we'll see how it works. In April, Tillerson asked all UN members to fully implement sanctions; to cut or downgrade diplomatic relations with North Korea; and increase its financial isolation. And he issued a threat to UN members that don't comply.

"It's a pressure campaign that has a knob on it," Tillerson told State Department employees May 3. "I'd say we're at about dial setting five or six right now."

Though Tillerson did not specify how those third-country sanctions would work, part of the strategy involves asking countries around the globe to scale back their diplomatic relationships with Pyongyang.

5. Regime change

The Trump administration has sent mixed messages on this. In April, Tillerson said regime change -- removing leader Kim Jong Un -- wasn't the goal.

In July, CIA Chief Mike Pompeo said it might be. He said that while a denuclearized Korean peninsula would be great, the most dangerous thing about those weapons is the man who wields them: "So from the administration's perspective," he said, "the most important thing we can do is separate those two. Right?"

Pompeo admitted during a Q&A that there are risks to this approach, namely, what would come next?

6. Military force

No one wants this, but the Trump administration says it's ready to use muscle to back its diplomacy. Analysts raise a couple of issues, one being former Secretary of State Colin Powell's Pottery Barn rule of foreign relations: you break it, you own it. A military operation against North Korea would saddle the US with expanded costs and responsibility on the peninsula. It would roil Asia and China, perhaps with unintended consequences. And while all war game scenarios show the US winning a military confrontation, that victory comes at the cost of hundreds of thousands of deaths, mostly in South Korea.