Why indeed? Oh, we can think of a couple of reasons. Donald Trump and Theresa May put on their best faces for the cameras after a flurry of controversy yesterday, in which the Sun published criticism of May by Trump as she was hosting him at a dinner. Both leaders claimed the relationship remained strong:

U.S President Donald Trump said on Friday he and British Prime Minister Theresa May had “probably never developed a better relationship” than during a dinner on Thursday.

May’s spokeswoman echoed the sentiment, and echoed Trump’s remarks on trade:

“Trade is one of the top items for discussions between the president and the PM today and … we are confident that we can do a good trade deal with the U.S.,” the spokeswoman told reporters.

“The prime minister has a good relationship with the president.”

No, really … they want to know why you’re asking:

Trump rolled his eyes and looked irritated when asked if he regrets the comments he made to the British tabloid while sitting next to May at her country estate Chequers. May also appeared annoyed by the question.

The White House tried patching up the diplomatic faux pas with a statement last night from Sarah Sanders:

In the wake of the interview, White House press secretary Sarah Sanders issued a statement that appeared aimed to smooth things over.

“The President likes and respects Prime Minister May very much. As he said in his interview with the Sun she “is a very good person” and he “never said anything bad about her”. He thought she was great on NATO today and is a really terrific person. He is thankful for the wonderful welcome from the Prime Minister here in the U.K,” Sanders said.

Today’s display makes it seem like the effort worked, but it raises questions about what will happen in Trump’s next effort with Vladimir Putin. So far Trump has reserved almost all of his criticism for America’s allies while putting on his best diplomatic efforts for what he calls the West’s “competitor,” but which most would call at least an “opponent,” if not a malevolent and dangerous enemy. Trump does not like to lose an argument, and the worry is that he might be tempted to go easy on Putin to justify both his attacks on NATO and his long-expressed desire to strengthen ties with Moscow. Trump’s rhetoric so far has featured a lot of short-term tactical thinking and very little long-term strategic or even diplomatic considerations.

On trade, though, both Trump and May have nothing but long-term strategy to discuss. While the UK remains in the EU, May can’t negotiate separate trade agreements. Trump’s frustration on May’s soft-Brexit plan is justified in that sense, even if publicly airing it while May hosts him was inconsiderate and unwise. (Imagine May coming to the US and publicly criticizing Trump’s NAFTA renegotiation as Trump welcomed her into the White House, for instance.) Her Brexit plan may not allow her to set terms with much difference than those of the EU for several years. They can talk trade all they want, but unless the UK bails out of the EU unilaterally, it’ll be years before they can control bilateral trade conditions enough to make it worthwhile.

It’s not likely May’s government will survive long enough to be the negotiating partner when the UK really does have that control. Trump might want to consider what the alternative would be if May falls. It might be his friend Boris Johnson, but it could very well be Jeremy Corbyn if Trump keeps undermining May publicly. The welcome in the UK won’t get warmer under those circumstances.