Like the one-sided bromance it always was, the Trump-Putin relationship is officially on the rocks — for now at least — with the US president declaring the first sanctions of his administration on Russia’s two largest oil companies.

It’s a new and important milestone in the nearly four-year-old war of aggression launched by Russia against Ukraine.

How effective those sanctions on Russia’s two major oil companies will be largely depends on US follow-through, including the possibility of secondary sanctions long threatened by President Trump against countries continuing to do business with Russia, thus funding its war machine.

The Treasury Department imposed sanctions Wednesday against Rosneft and Lukoil and their nearly three dozen subsidiaries, declaring in a statement that the action was being taken “as a result of Russia’s lack of serious commitment to a peace process to end the war in Ukraine.”

The action followed a week of fits and starts in those peace negotiations, including the cancellation of a planned summit meeting between Trump and President Vladimir Putin in Budapest, a sign that Trump may, at long last, have realized the Russian leader had long been playing him like a fiddle.

“I don’t want to have a wasted meeting. I don’t want to have a waste of time here. I’ll see what happens,” Trump told reporters in the Oval Office after the meeting’s cancellation.

But nothing says “we really mean it” like the kind of punishing sanctions designed to further squeeze the Russian economy. The sale of oil and gas accounts for about a quarter of the Russian budget, and Russia produces about 11 percent of the world’s oil supply.

Oil prices increased nearly 5 percent worldwide Thursday in response to the move. India, among Russia’s largest buyers of oil, was planning to at least reduce, if not end entirely, imports of Russian crude.

“Recalibration of Russian oil imports is ongoing,” a spokesperson for the privately held Indian refiner told Reuters, noting the company intended to abide by whatever government rules were put in place.

Of course, evading restrictions has become a way of life for Russian tankers and bankers, and the current sanctions will be no different unless the United States remains vigilant in enforcing these most recent rules. Some, including Ukrainian President Volodymyr Zelensky have in addition urged so-called secondary sanctions aimed at third-party countries and entities, like China and Chinese banks, for helping that evasion.

The European Union also moved this week to target the “shadow fleet” that carries Russian oil and liquified natural gas in obvious violation of sanctions.

But wars are not halted by sanctions alone.

And while Ukraine has made remarkable strides in building up its own drone industry and deploying those effectively on the battlefront, and European allies have pitched in buying American-made weaponry for Ukraine’s use, there are gaps in Ukraine’s ability to take the fight to Russia.

Zelensky has most recently petitioned for long-range Tomahawk missiles, something he didn’t get from the US administration this week.

“There is a tremendous learning curve with the Tomahawk,” Trump said Wednesday following a meeting with NATO Secretary General Mark Rutte. “It’s a very powerful weapon, very accurate weapon, and maybe that’s what makes it so complex. But it will take a year. It takes a year of intense training to learn how to use it, and we know how to use it, and we’re not going to be teaching other people. It will be too far out into the future.”

However, The Wall Street Journal reported this week that Trump did lift a restriction on Ukraine’s use of other long-range missiles, the British-supplied Storm Shadow. That allowed Ukraine to use the missiles to strike a Russian plant in Bryansk that produces explosives and rocket fuel.

Trump has called that report fake news on social media, adding, “The US has nothing to do with those missiles, wherever they may come from, or what Ukraine does with them.” But as the Journal reported, the missiles do use US targeting data — a nicety the president has wisely decided to overlook it seems.

Ukraine in recent days has paid the price in a very real way for the breakdown of cease-fire negotiations and for Trump’s newly found realism on dealing with Putin. Shortly after the Budapest summit was canceled, Russian drones hit a preschool in Kharkiv, and while the 48 children attending it were safely evacuated, one adult was killed, seven people were wounded, and the school and an apartment building were destroyed.

A Russian drone strike Thursday killed two Ukrainian journalists– bringing to 135 the number of media workers killed during the war.

Such is life — and death — in this continuing war.

Whatever the United States can do to bring the war to Putin’s doorstep — with sanctions and the easing of needless limitations on Ukraine’s ability to fight its own battles — is the only way to bring a ruthless tyrant to the bargaining table.