Washington (CNN)President Donald Trump's blistering tongue and stinging tweets spare almost no one. But there are two blatant exceptions to his saturating rhetorical fire: Vladimir Putin and Stormy Daniels.
Is Trump's silence on Putin, Daniels telling?
The President never shrinks from slamming his perceived foes from Rosie O'Donnell to the cast of "Hamilton," to slain political enemies like "low energy" Jeb Bush and estranged political guru "sloppy" Steve Bannon.
He's jabbed allied leaders such as Britain's Theresa May and Germany's Angela Merkel, torched whole nations, such as Pakistan and Belgium, and teed off against retail giants including Macy's and Amazon.
But the ex-KGB man in the Kremlin, who is accused of meddling with US democracy and ordering a nerve agent attack in Britain and the porn star who told 20 million "60 Minutes" viewers she had unprotected sex with Trump each get a mysterious pass from the President's attacks.
Those omissions were especially noticeable on Monday as the Russian President and Daniels were vying for top billing on news shows.
As tempting as it must have been to hit back at Daniels, Trump kept quiet, possibly seeking to avoid being drawn any deeper into a thicket of litigation by three women who have brought sex-related civil cases to which he is linked.
Also Monday, Trump's White House rolled out its toughest action yet on Russia, kicking out 60 diplomats over the attempt by suspected Kremlin agents to assassinate a former Russia spy in the sleepy English city of Salisbury.
But Trump, consistent with his practice of never personally calling out or criticizing Putin, was nowhere to be seen.
The reasons for Trump's reticence were not clear, since he's not talking. But there will be suspicions that he's keeping quiet because both Putin and Daniels may know something about the President's past that could hurt him.
After all, Daniels' lawyer Michael Avenatti insists he has evidence supporting her claims about an alleged 2006 affair with Trump as she seeks to invalidate a nondisclosure agreement. Trump has denied the affair, the White House says.
And special counsel Robert Mueller's request for documents on Trump Organization business in Russia could suggest he wants to know if there is any activity the President would be keen to cover up and that could help provide a motive for a potential attempt to obstruct justice. Trump, again, has denied any wrongdoing.
When it comes to Daniels, Trump's aides have advised him that lashing out would only fuel to the story. He appears to be taking a similar approach to Karen McDougal, a former Playboy model who revealed an alleged affair with Trump in a CNN interview last week.
The President believes the Daniels allegations are a 'hoax' designed to damage him politically, Chris Ruddy, a close Trump ally and CEO of Newsmax, told ABC News on Sunday. Trump has also seized on Avenatti's Democratic connections to portray him as an operative with an ax to grind.
In recent conversations Trump has asked friends and outside advisers whether he should publicly defend himself, indicating that he's eager to put the allegations to rest.
But even allies who ordinarily reinforce the President's combative instincts have warned that wading into such a torrid matter would appear unpresidential. That has not stopped Trump from complaining about constant news coverage of Daniels and a lack of allies on television defending him.
There could also be legal implications -- after all, former NBC "Apprentice" contestant Summer Zervos was able to launch a defamation action even after the statute of limitations had passed on her original harassment suit because Trump branded women who accused him of inappropriate behavior as liars.
At least for now, Trump plans to heed warnings to stay quiet and he is not scheduled to take questions from reporters this week. But in a possible sign of his concern, he invited his personal lawyer, Michael Cohen, who is embroiled in the Stormy Daniels case for dinner at Mar-a-Lago on Saturday night.
Still, Trump routinely changes his mind quickly, and could easily throw his aides for a loop by tweeting or offhandedly commenting on the issue.
The White House wouldn't say on Monday whether Trump had viewed the "60 Minutes" interview on CBS in which Daniels described playfully spanking him with a magazine and reluctantly having sex. But there were indications Trump spent Sunday evening and Monday morning reacting to the allegations.
"So much Fake News. Never been more voluminous or more inaccurate," he tweeted.
Later, White House spokesman Raj Shah said Trump "doesn't believe that any of the claims Ms. Daniels made in the interview are accurate."
Rumors that Russia could have some material about Trump's past have been floating around Washington since 2016 and were followed by revelations the next year about a dossier written by former British spy Christopher Steele.
US intelligence officials have said that they have reached no conclusion on whether the Russian government does have any compromising information about the President. Trump has slammed the document as "bogus" and says it was part of a Democrat-funded bid to derail his election victory.
John Brennan, who served as CIA director in the Obama administration, last week sparked a furor by warning that Russia may have damaging material, known as Kompromat, on Trump.
"The fact that he has had this fawning attitude toward Mr. Putin, has not said anything negative about him, I think continues to say to me that he does have something to fear and something very serious to fear," Brennan said on MSNBC.
While Brennan did not cite any evidence, Trump's warm relationship with Putin is a puzzle and at times has verged on hero worship -- even as US-Russia relations have plummeted.
The President has enthusiastically sought out Putin at international summits, repeatedly praised his authoritarian leadership style during the campaign and pointed out that the Russian strongman once called him a "genius."
Trump has also repeatedly spoken about his desire to forge a strong relationship with the Russian leader even though Washington and Moscow's geopolitical interests are diverging.
Trump said last week his call with Putin was "very good" and hopes to meet him soon to discuss Ukraine, Syria, North Korea and a US-Russia arms race.
But the President's failure to raise the nerve agent attack in Britain and his decision to defy advisers and congratulate Putin on his election victory sparked another flurry of speculation about their cozy relationship.
There are other credible explanations for Trump's felicity towards Putin. One could be stubbornness, since most of Washington is trying to force him to toughen up and the President reacts poorly to such pressure.
Another might be the President's inability to divorce the question of US-Russia relations from what he believes are unfair allegations that Moscow intervened in the US election to help him win.
Given Trump's unpredictability, and impulse driven behavior, there's no guarantee that even Putin and Daniels will remain safe from attack forever.
Trump has discarded his aides' advice in the past to remain silent on a variety of issues, most notably on Mueller. And his personal definition of what constitutes presidential behavior has never adhered to norms.
Avenatti understands his foe well and appeared to be goading the President into lashing out, highlighting two areas where Trump has historically struggled to remain on the sidelines.
"The ratings for my client's @stormydaniels appearance on @60minutes last night CRUSHED (BY MILLIONS) any Apprentice show in the last ten years as well as Mr. Trump's Nov 2016 appearance," he tweeted Monday.
Earlier, he hinted at revelations that could also spur presidential outrage.
"She can describe his genitalia," he said on NBC's "Today" show.