But those concerns didn't prevent Trump from scheduling a stop in the country, where he's expected to praise Poland's success in meeting its North Atlantic Treaty Organisation defense spending pledge and tout new exports of United States liquid natural gas in a bid to wean the country from Russian-produced energy.
The Polish government has expressed excitement about Mr Trump's stop in Warsaw - in contrast to some of the frostier reception he is expected to receive in western European capitals - with defence minister Antoni Macierewicz saying the visit shows "how much Poland's place in geopolitics and world politics has changed".
The still-novice U.S. president will deliver a speech at Warsaw's historic Krasinski Square on Thursday and also meet with Baltic, Balkan and central European leaders while in the Polish capital.
With those investigations hanging heavy in the air, there is little expectation the meeting will produce significant progress on hard issues such as the crisis in Ukraine or the conflict in Syria.
US President Donald Trump touched down in Warsaw late on Wednesday evening to talk security and trade with his Polish counterpart Andrzej Duda and meet regional leaders before heading to Germany for a G20 summit.
In that quest, the embattled USA president will get a sizeable assist from Poland's ruling conservative party, which said it is laying on free buses to ferry in admirers.
Warsaw and three Baltic states have also voiced their opposition to Russia's plan to build a gas pipeline to Germany.
"Although the president himself has not spoken to the family, he does not want to pressure them in any way, members of the administration have spoken to the family in calls facilitated by the British government", White House director of media affairs Helen Aguirre Ferré said. "This is the single image that we remember from 1989", he said.
After this trip, the president will be back in Europe soon for a mid-July visit to France to celebrate Bastille Day alongside new French President Emmanuel Macron. This American-drawn distinction between the Old Europe and the New not only signaled problems within the U.S. -EU security arrangements, it also created serious diplomatic tensions ahead of European Union enlargement decisions over the next two months.
And he will promote trade at talks with Central and Eastern European leaders. It's also a regular customer for US military equipment. Poland is meant to admit 9,287 asylum-seekers but has taken in none.
It would be one thing if the risks of a Trump visit had a chance of being offset by great potential benefits.
As with that earlier tour, though, any warm glow is likely to be short-lived before Mr Trump is confronted with the reality of his standing in the world order.
The presidential plane Air Force One took off from Andrews air force base, near Washington, to 08H15 with Donald and Melania Trump at its edge. "They just love him, the people in Poland-they just really love him".
Gary Cohn, director of the US National Economic Council, leaving the White House with the Trumps on Wednesday.