Bill Browder, Putin's number one foreign enemy, gives Trump some sage advice on his scheduled meeting with Putin.

Excerpt:

Putin has a weak hand and is always bluffing. Just by meeting him, you’re giving him a huge gift. The President of the United States is the most important and powerful person in the free world; in contrast, the President of Russia is practically nobody. The Russian economy is roughly equivalent to the state of New York’s. The Russian military budget is 90% less than that of the United States, on par with the U.K. or France. All of Putin’s geopolitical theatrics are him showing his weakness. At best, he’s got a pair of twos. The United States has a full house.

Putin is a bald-faced liar. You can’t believe a word Putin tells you. His track record of lying is legendary and well-documented. He lied about the “little green men” invading Crimea; he lied about Russia taking away Syria’s chemical weapons; he lied about who shot down MH17; he lied about Russian doping at the Sochi Olympics; he lied about the recent poisoning of the Skripals in the United Kingdom; and he lied about Russian involvement in the recent U.S., U.K., French, German, and Italian elections. Whatever he tells you, it’s not true.

Putin doesn’t negotiate. Whatever you offer will simply become the beginning point of your next negotiation. Don’t be offended when he does this to you. He does it to everybody. In 2001, President George W. Bush famously looked Putin in the eye and saw his soul. Last year, I had lunch with President Bush and asked him about it. In short, he said that each of their dozens of following meetings and conversations were disastrous. In 2009, President Barack Obama tried to clean up the situation by offering Russia a “reset.” All that did was embolden Putin further. He knew that he could operate with impunity and that the United States wouldn’t do a thing. Putin views compromise and engagement as weakness. Any offer of these will lead to him doing more malicious and awful things around the world.

Putin has the temperament of a cold-blooded killer. Most civilized people can’t imagine what he is capable of. He’s not like any leader of a sovereign state, but more like drug lord Pablo Escobar—but with nukes. In one afternoon, Putin likely goes from discussing tax policy with his economic advisers to planning targeted assassinations of dissidents and business competitors with his secret police.

Putin values money far more than human life. I’ve discovered that the only way to touch Putin is by going after his money and the money of his cronies. I figured this out with Magnitsky sanctions. These have been enacted by the United States, the United Kingdom, Canada, and the Baltic states. Since Putin and his officials kill people and steal money in Russia, and then keep that money in the West, Magnitsky sanctions put at risk his entire mafia-like operation.

Mr. President, the only way to deal with a person like Vladimir Putin is to contain him, not to engage him. He will lie to you, flatter you, trick you and betray you. The only message to you can give him in Helsinki on July 16 is that America is a proud and strong country which can and will stop him.

TIME