Nuclear weapons provide such a great strategic advantage, even if never used, that nations that come close to developing them can almost never be persuaded to back down. Whether enemy or ally, most nations on the threshold of becoming a nuclear power cannot be persuaded to reverse course, and nations that already have the bomb have shown strong resistance to stopping further tests. Here are the top five examples:

5. France, 1990s: In 1995, French President Jacques Chirac announced that France would resume nuclear testing in the South Pacific. The announcement set off a storm of international controversy, and Greenpeace sent its ship, the Rainbow Warrior II, into the area to disrupt French plans. The French seized the ship and went ahead with six of their eight tests, finally canceling the last two because of international pressure.

4. Israel, 1960s: The U.S. suspected Israel of developing a nuclear weapons program under the guise of a peaceful nuclear energy program. The Soviet Union told President John F. Kennedy that they had discovered an Israeli nuclear facility, and Israel assured Kennedy, falsely, that it was for peaceful purposes, convincing American inspectors who arrived at the site. Israel is today widely suspected of possessing nuclear weapons.

3. Pakistan, 1990s: Though Pakistan began developing nuclear weapons in the 1970s, it only emerged onto the world stage as a nuclear power in 1998, after rival India detonated its own weapons. There was a period of several weeks in the interim in which President Bill Clinton tried to persuade Pakistan to avoid going nuclear, using promises of aid and threats of sanctions. In the end, all effort at persuasion was to no avail.

2. North Korea, 1990s-2000s: Both the Clinton administration and President George W. Bush attempted to use negotiation to dissuade the North Koreans from pursuing nuclear weapons. North Korea agreed, in return for aid and other commitments, to halt its nuclear ambitions both in 1994 and 2005. Eventually, it gave up all pretense and broke its agreements, while developing an aggressive ballistic missile program.

1. Iran, 2000s-2010s: Iran has pursued a very ambitious nuclear program, insisting that its intentions are merely scientific as it enriches uranium ever closer to weapons-grade levels of purity. It has flouted a series of UN Security Council resolutions as well as the Non-Proliferation Treaty, and has repeatedly deceived international inspectors. Despite hopes for a shift, many expect it to renege on any nuclear agreement.

The only example of a country actually giving up its nuclear weapons after having developed them is South Africa, which destroyed its weapons and abandoned its weapons program during the transition from white minority rule to democracy. The former regime had retained the weapons to protect itself, theoretically, from armed insurrection from within and possible attack by regional enemies with Soviet backing.