President Trump and Russian President Vladimir Putin in 2017. (Evan Vucci/AP)

THE REASONS for the tension between the United States and Russia are well-established. Russia seized Crimea from Ukraine, instigated a war in eastern Ukraine, intervened to save the dictatorship of Syrian President Bashar al-Assad, interfered in the U.S. presidential election campaign to harm Hillary Clinton and help Donald Trump, poisoned a former intelligence officer on British soil and continues to meddle in the elections of other democracies. Yet on Wednesday in the Kremlin, President Vladimir Putin brushed it all aside and delivered the Russian “maskirovka,” or camouflage, answer that it is all America’s fault.

Meeting with John Bolton, the president’s national security adviser, Mr. Putin declared that the tensions are “in large part the result of an intense domestic political battle inside the U.S.” Then Mr. Putin’s aide Yuri Ushakov insisted that Russia “most certainly did not interfere in the 2016 election” in the United States. On Thursday morning, Mr. Trump echoed them both on Twitter: “Russia continues to say they had nothing to do with Meddling in our Election!”

Why is Mr. Trump kowtowing again? The U.S. intelligence community has concluded that Russia did attempt to tilt the election using multiple campaigns, including cyberintrusions and insidious social media fakery. Would it be so difficult to challenge Mr. Putin about this offensive behavior? A full accounting has yet to be made of the impact on the election, but Mr. Bolton did not mince words last year when he described Russian interference as “a true act of war” and said, “We negotiate with Russia at our peril.” And now?

Summits can be productive, even — maybe especially — when nations are at odds. In theory, a meeting between Mr. Trump and Mr. Putin, now scheduled for next month in Helsinki, could be useful. But a meeting aimed at pleasing Mr. Putin is naive and foolhardy. A meeting aimed at pleasing Mr. Putin at the expense of traditional, democratic U.S. allies would be dangerous and damaging.

Just as Mr. Bolton was flattering Mr. Putin, Russia was engaging in subterfuge on the ground in Syria. The United States, Russia and Jordan last year negotiated cease-fire agreements in southwestern Syria, along the border with Jordan and the Golan Heights. In recent days, the United States has warned Russia and its Syrian allies not to launch an offensive in the area, where the rebel forces hold parts of the city of Daraa and areas along the border. The State Department vowed there would be “serious repercussions” and demanded that Russia restrain its client Syrian forces. Secretary of State Mike Pompeo called the Russian foreign minister, Sergei Lavrov, saying an offensive would be unacceptable. All to no avail; Syria is bombing the area.

This is what happens when Mr. Trump signals, repeatedly, that he is unwilling or unable to stand up to Russian misbehavior. We are on dangerous ground. Either Mr. Trump has lost touch with essential U.S. interests or there is some other explanation for his kowtowing that is yet unknown.