With the news from the always well-informed and reliable Kim Strassel and Andy McCarthy that there was probably an FBI informer in the Trump campaign, the tide in the investigative struggle turns decisively from the floundering, flailing effort to pin something grievous on the president to the rising wave of curiosity about the extent to which the Justice Department was politicized under the Obama administration in favor of the Clinton campaign. This could contain the elements of a scandal almost as great as would have occurred if there had been the slightest evidence to support the notion that a presidential candidate had concerted with a foreign power to rig an American presidential election. I place my bets with Ms. Strassel and Mr. McCarthy, and expect the current of suspicion of the Justice Department to accelerate with the FBI inspector general’s next report, on official handling of the Clinton email issue.

If Mueller doesn’t repurpose his mandate to focus on the conduct of the Democrats who commissioned the Steele dossier, he will probably have to be satisfied with written responses from the president to written questions relevant to Mueller’s mandate, or an invitation from the president, who should not respond to a subpoena to appear before a grand jury, to indict him and show his evidence. (It is very unlikely that Mueller has any.) The old special prosecutor’s game of co-opting the Congress to corner the president won’t fly. Even if the Democrats win the House and vote impeachment for obstruction because Trump refuses to go before a grand jury, there is no chance of conviction without evidence, and Comey, McCabe, Clapper, Brennan, and all the rest will still have to face the music for lying under oath. The people are the jury, and Russian collusion is a clunker, unless Mueller has an intellect-transplant and starts to chase real legal problems involving Trump’s enemies.

(One minor point: Alexander Downer, who had the boozy encounter with George Papadopoulos in the Kensington Wine Rooms, is not “an Australian diplomat.” He is an unsuccessful leader of the opposition who was rewarded when his party came to office with representing Australia in London. Downer has no career diplomatic standing or connections, and what went on in that conversation about the Trump and Clinton campaigns was rank gossip and hearsay.)

There is nothing to do but wait for the next flaking off of real facts and findings. The anti-Trump case has been based on fantasy and smears since it started.

On to North Korea and Iran. The wails of those who warned that the two mad boys-with-toys, Kim and Trump, would blow up the world, have now turned to dire warnings that Trump is unprepared and will be hosed by the wily chief of the Hermit Kingdom. Kim is coming to the party at Singapore only because he has bought the face-saving formula of recognition, end of sanctions, and of talk of reunification and absence of nuclear weapons from South Korea (where there have never been any permanently deployed), rather than have his nuclear-relevant sites razed by U.S. conventional attack, along with cruise-missile carpet-bombing on the artillery aimed at Seoul, South Korea, from the foothills just across the DMZ. Kim will make the deal, given the alternative, but the negotiation has already happened. This Kim, who appeared so ludicrous, could be incomparably the greatest and most successful Kim of all. (Kim Il-sung and Kim Jong-il just festered in their penurious artificial prison-nation, completely dependent on the Chinese, who pretended to demur but enabled the Kims to irritate the West.)

Something similar can be done with Iran. That politically and economically palsied country is grossly overextended, trying to bankroll and partially fight civil wars in Yemen and Syria and underwrite the anti-Israeli skirmishing in Lebanon and Gaza. Any serious reimposition of sanctions by the United States (and it can kick the European allies into line, if not lock-step, as commerce with the U.S. is worth to them a high multiple of the value of trade with Iran), when coordinated with Israeli escalation against Hezbollah and Hamas in Lebanon and Gaza, and Saudi intensification of the civil war in Yemen, will force Iran to contract its grandiose play for resurrection of the ancient Persian Empire of Cyrus, Darius, and Xerxes, which threatened ancient Greece. The British, French, and German leaders can play the analogous role to that of Chinese president Xi Jinping opposite North Korea, though Iran is much less dependent on them and is a substantial country of ancient standing and not just an artificial creation like North Korea, which was set up at the line where it was determined whether the Japanese occupying forces in Korea would surrender to the Russians or the Americans at the end of World War II.

The United States can force Iran to expand the ridiculous agreement negotiated by Obama and the European allies and Russia and China, to be a permanent renunciation of nuclear weapons, including missile and warhead development, and wind-down of Iranian military and terrorist meddling, by sanctions and the threat of military elimination of the Iranian military nuclear program (with the encouragement and if necessary the participation of the Egyptians, Saudis, and Israelis). Iran is less advanced in military nuclear terms than North Korea, its sites would be resistless against American attack, and Iran has nothing like the sponsorship North Korea long enjoyed from China. It is a stronger country than North Korea, but almost as friendless and with a much less docile population. The choice will be real renunciation of Iran’s nuclear weapons and of its support of terrorist proxies, presented as a success and not a humiliation, or complete economic impoverishment and direct military air attack of unanswerable precision and force on its nuclear-arms program. If Kim can figure it out, the ayatollahs should. The Europeans, though they cannot be trusted for much else, can deliver that message.

The supreme irony of these issues is that contrary to conventional opinion, President Trump is the last bulwark of nuclear non-proliferation.

The supreme irony of these issues is that contrary to conventional opinion, President Trump is the last bulwark of nuclear non-proliferation. The nuclear powers (U.S., U.K., Russia, France. China, India, Israel, and Pakistan) are a club that has pledged to try to disarm and has (wisely) ignored the pledge, as retaliation is the only reliable guarantee against another world war (though South Africa after the end of the apartheid government and Ukraine after the dissolution of the USSR commendably did disarm). None of the nuclear powers has behaved irresponsibly with its arsenals, but North Korea and Iran have both threatened to destroy other countries and are completely untrustworthy politically. In disarming them, with whatever face-saving is appropriate (and with any luck the rotten and medieval despotism in Iran could implode anyway), President Trump will at least keep nuclear non-proliferation on the rails. If North Korea and Iran become military nuclear powers, so will Japan, South Korea, Indonesia, Egypt, Saudi Arabia, and Turkey, and that will just be the beginning — the whole system for avoidance of great wars will pass from nuclear abstinence to missile defense and massive retaliation. Again, the United States is the only country (followed distantly by Israel) that has any idea of how to stop incoming missiles with nuclear warheads, but it would be a desperate extremity to retreat to that point for assurance of avoidance of nuclear war.

We are already facing the increasing possibility of terrorists’ putting missiles in civil airliners or container ships or even suitcases, and enabling the nuclear weaponization of terrorist states such as Iran is an abominable practice of appeasement. The unsuspecting world will have reason to be thankful for President Trump.