(CNN) In death, Senator John McCain has let loose an international outpouring of sympathy, respect and thinly veiled criticism of President Trump.

The tributes flooding in from world leaders seem to amplify McCain's principled stand against his President.

Britain's Prime Minister Theresa May, who was criticized publicly by Trump last month, said that, "John McCain was a great statesman, who embodied the idea of service over self."

It is hard to read those words and not hear frustration and understand the subtle subtext.

Germany's Foreign Minister Heiko Mass -- whose country is at loggerheads with Trump, in particular over NATO -- was less delicate: "John McCain was a convinced advocate of a strong and reliable transatlantic partnership, especially in difficult times. He believed in our shared values and principles."

Maas leaves little doubt whom he'd have rather seen in the White House.

The list goes on.

Europeans are clearly troubled by Trump's apparent willingness to give new friends like Vladimir Putin -- whom McCain strongly campaigned against -- preferential treatment over the US's traditional allies.

In those countries formerly under the Soviet Union's iron grip, tributes show a longing for the kind of constancy in US relations that McCain championed.

Slovakia's President Andrej Kiska lauded McCain as "a man of courage, of strong principles and tireless fighter for the values we share on both banks of the Atlantic."

Estonia's Prime Minister Juri Ratas said "he was a courageous and determined man, showing a remarkable understanding of global affairs. His contributions into the security of the Baltic states will never be forgotten."

Lithuania's President Dalia Grybauskaite described McCain's passing as "a big loss not only to our region but also to the whole world."

And Latvia's President Raimonds Vejonis, completing the triumvirate of Baltic leaders who have been rattled by Trump's apparent ambivalence to their concerns about Russian aggression, added that McCain was "a true defender of democracy and freedom, and a great friend of Latvia."

Sen. McCain listens as former FBI Director James Comey testifies in front of the Senate Russia hearing.

Friend of many people

To imply McCain has garnered such glowing tributes simply to sound off frustration about Trump would be wrong though.

He was respected for who and what he was. He traveled the world as a tireless advocate for the United States, and made many friends along the way.

I remember meeting him in Afghanistan -- at that time one of the wildest and more dangerous places a US Senator could go -- he was relentless in finding out the facts for himself, whatever potential harm that may have put him in.

Afghan President Ashraf Ghani on Sunday paid him high praise: "Senator McCain served his country honorably in uniform and his service in the Senate is truly exemplary. We will remember his dedication and support towards rebuilding Afghanistan."

Where McCain had in the very real sense of the word been in harm's way -- a prisoner of war for five and half years in Vietnam, from 1967 to 1973 -- he was remembered by Vietnamese and Americans alike with flowers and tributes.

One American visiting the monument near Truc Bach Lake outside Hanoi, where McCain's bomber jet crashed 51 years ago, told Reuters news agency that McCain "was the last guy I ever voted for as President."

John McCain is examined by a Vietnamese doctor in 1967 after being captured in Hanoi.

Today's world leaders, who have no vote in US Presidential elections, seemed to give a nod towards a man they'd pick over the present incumbent.

They have done this not collectively in a carefully choreographed joint statement, but individually picking what's important for them and their countries in what amounts to a fusillade of criticism aimed at Trump.

Australia's new Prime Minister Scott Morrison said that "Senator John McCain was a true friend of Australia who was committed to strengthening the alliance between our two nations."

President Trump had a disastrous relationship with Morrison's predecessor Malcolm Turnbull, abruptly ending their first phone call days into office over a disagreement about refugees.

Of course, any of these tributes can be explained away for simply what they are -- well-intentioned condolence.

It is after all the skill of any accomplished politician to find phrases that appeal to all. What I hear may not be what everyone takes away.

However, it would feel to me naive not to grasp that, at the very least, what has been said in tribute to McCain -- either intentionally or unintentionally -- amounts to the broadest sounding so far of global disquiet among America's allies with Trump.

In that alone, Senator John McCain has been paid the highest accolade of all.