As nervous NATO allies meet with Secretary of Defense James Mattis for the first time, it is worth noting that Donald Trump's drumbeat of calls for those allies to pay up, or else, contains one clear exception — one that coincides with his own business interests.

As Secretary of Defense James Mattis tries to reassure allies of the administration’s commitment to NATO at talks in Brussels this week, Reuters reports that Donald Trump’s prior criticisms of the NATO alliance have some members on edge. One of the more shocking things that Trump has said about NATO is that the United States might not honor alliances if member countries do not pay up.

One aspect of Trump’s NATO policy, however, has gone largely unnoticed by the press. Since being inaugurated, Trump has had many phone calls with world leaders, including NATO members. According to the White House’s official readouts of those calls, each conversation with a NATO head of state included variations on a common theme.

From the readout of Trump’s call with Chancellor Angela Merkel of Germany:

(O)ur common defense requires appropriate investment in military capabilities to ensure all Allies are contributing their fair share to our collective security.

With French President Francois Hollande:

President Trump reaffirmed the U.S. commitment to NATO and noted the importance of all NATO Allies sharing the burden on defense spending.

With Prime Minister Paolo Gentiloni of Italy:

President Trump reiterated the U.S. commitment to NATO and emphasized the importance of all NATO allies sharing the monetary burden of defense spending.

With NATO Secretary General Jens Stoltenberg:

The leaders discussed how to encourage all NATO allies to meet their defense spending commitments.

And with Prime Minister Mariano Rajoy of Spain:

President Trump reiterated the U.S. commitment to the North Atlantic Treaty Organization (NATO) and emphasized the importance of all NATO allies sharing the burden of defense spending.

There was something different, however, about Trump’s call with President Recep Tayyip Erdoğan of Turkey:

President Trump reiterated U.S. support to Turkey as a strategic partner and NATO ally, and welcomed Turkey’s contributions to the counter-ISIS campaign.

In every call with NATO leaders that the White House read out, Trump complained about spending on defense, except on his call with Erdoğan — despite the fact that Turkey, like many NATO countries, falls short of the defense spending benchmark of two percent of GDP.

Unlike those other countries, though, Turkey happens to be the location of a luxurious Trump property, Trump Towers Istanbul. Additionally, a company linked to the Turkish government retained disgraced former National Security Advisor Michael Flynn’s lobbying firm, right around the same time Flynn advocated for the extradition of the Pennsylvania cleric whom Erdoğan blames for a failed coup attempt.

Trump’s conflicts taint his presidency nearly every day, and now, as he shakes down other allies for contributions, he has brought pay-to-play corruption into the world’s oldest and most important alliance.