In 1994, after the breakup of the Soviet Union, Ukraine agreed to give up its nuclear weapons in exchange for security guarantees. That didn't work out so well.

Libya, under Muammar Gaddafi, agreed to stop its nuclear weapons program. Gaddafi was overthrown and killed by insurgents supported by foreign governments.
Iraq, under Saddam Hussein, also stopped its nuclear weapons program. Saddam Hussein was overthrown and killed.
In contrast, North Korea finished its program. It now seems secure against foreign intervention.
Iran saw what happened and decided it needed nuclear weapons.
Countries that have nuclear weapons survive, those that don't, don't.

In 2017 60% of South Koreans supported having nuclear weapons.

Taiwan had a nuclear weapons program, but discontinued it because of pressure from the United States.

Here are ten ideas for dealing with Vladimir Putin and Ukraine.

1. Ask President Zelensky what Ukraine needs.

2. Supplies.
This has largely already been done. The U.S. has shipped tens of thousands of guns to Ukraine. It also included Javelin anti-tank missiles. Other supplies should include: food (for an extended resistance), water purification equipment, communications equipment (for showing the outside world what is going on). Elon Musk has helped with the latter.
Philip Breedlove and Kurt Volker. have more detailed suggestions.
Perhaps something like the Berlin airlift could be arranged.

3. Sanctions.
All international organizations, that haven't already done so, should be pressured into expelling Russia. A law could prevent U.S. companies from paying money to any organization that doesn't cooperate.

4. Oil and gas.
Cut off or reduce Russia's oil and gas exports by flooding the market with oil and gas. The would include removing all restrictions on oil and gas production and eliminating all regulations restricting carbon dioxide. It would also help to appropriate money for coal gasification. The government could offer prizes for breakthroughs that lead to coal gasification. The prizes would be decided by a committee appointed by a bipartisan group of officials plus representatives of the coal industry.
Since federal regulations and interventions have made investments in oil and gas more risky, we would need direct Federal investments to compensate. Federal projects, such as a renewed Keystone XL, could also be exempted from State and Federal regulations.
An objection is that some projects would take years. Jay Leno said years ago that those objecting to drilling for oil said that it would take six years to get results. He asked: "Isn't that what they said six years ago?"
As a compromise, we could make appropriations in later years dependent upon Congressional hearings and findings.
Other analyses of oil and gas can be found in RealClearPolitics, RealClearEnergy, and the Wall Street Journal.

5. Indirect military intervention.
Supply some Ukrainian military officers with military drones which they could operate from a nearby country such as Poland.

6. Cyber warfare.
Launch a cyber attack against Russia, especially targeting its infrastructure (e.g. its power grid). Ukraine is already doing this. American and other hackers could help.
Hilary Clinton has endorsed this technique.

7. Weaken Trump's hold on the Republican party.
Have the 28 Republican Governors condemn Donald Trump's description of Vladimir Putin as "savvy". Start with the ones in deep blue states: Maryland, Massachusetts, Vermont.
Mike Pence is moving in this direction.

8. Invite Sweden and Finland to join NATO.

9. Reduce the nuclear threat.
Appropriate $100 billion to purchase the Russian nuclear arsenal. This would prevent a similar crisis from happening again. As a sweetener, the United Kingdom and France could agree to give up their nuclear weapons. They wouldn't need them if Russia disarms. This deal would not be attractive to Putin, but would be to his successor.
And, speaking of his successor:

10. Kill Putin.
Appropriate $100 million to be paid to any individual or group that assassinates Vladimir Putin. This would be fair because Putin tried to assassinate Volodymir Zelensky.
Putin tried to kill Sergei Skripal and his daughter Yulia in the United Kingdom. It caused the death of Dawn Sturgess. There is a historical precedent: during World War II, the British launched an operation to assassinate General Erwin Rommel.
Lindsey Graham has endorsed this idea.
As an alternative, we could appropriate a few billion dollars of direct foreign aid for Ukraine, then they could offer the bounty.
One problem is that the assassins might attempt it indirectly and anonymously. They would need a way to prove they did it without giving themselves away prematurely. This can be done by encryption. Using a RAM drive, write out the plan, encrypt it using a public key system such as RSA, encrypt the private key using a symmetric key system such as AES, then store the files in the cloud such as Microsoft OneDrive, Google Drive, Dropbox, or MEGA.

Montesquieu, in The Spirit of the Laws, wrote: "The corruption of each government almost always begins with that of its principles" (Book 8, Chapter 1). Monarchies depend on honor, despotisms on fear, and republics on virtue. When the foundation crumbles, the system collapses. In a despotism, when the people lose their fear, the despot falls. The public protests in Russia are a sign that the Russians are losing their fear.
The problem of course is that desperate men do desperate things. If Putin finds himself losing the war, or facing a revolution or coup d'etat, he could order an all out nuclear attack. A few months ago the Chairman of the Joint Chiefs of Staff, Gen. Mark Milley met with Gen. Valery Gerasimov, the chief of the general staff of the Russian Armed Forces. We need such communication, especially at lower levels, to reduce the risk of accidental nuclear war. There have been close calls before.
We need to deal with this problem before it mushrooms.

Posted 2022/March/05