Washington (CNN) As President Donald Trump concluded lunch with his British counterpart Friday, he appeared so enthralled at successfully executing his first bout of face-to-face diplomacy that he asked an aide to file away the menu card for safekeeping.

"Keep that safe," he said, according to a UK official. "I had lunch with the British prime minister."

Indeed, after a meal of braised beef and his favorite iceberg wedge salad, Trump had reason to believe his debut as a statesman was a singular success.

During an 18-minute news conference, he stuck rigidly to script touting the transatlantic special relationship, never veering into the conspiratorial areas that had distracted him the week prior. UK Prime Minister Theresa May, meanwhile, hailed him as a populist savior and announced the British Queen had invited him to London.

Two days and seven phone calls later, the glow of Trump's diplomatic coming-out has faded.

As he convened call after call to foreign capitals this weekend, it became clear his travel ban on certain Muslim-majority nations would create rifts with some of the United States' closest partners -- including with May herself -- and threaten to isolate Trump, the newest member of the global leaders' club.

Sitting stone-faced at his paper-strewn Resolute Desk Saturday, Trump sipped from a glass of Diet Coke as the businesslike German chancellor Angela Merkel explained US obligations under the Geneva Convention. The agreement requires the US to accept refugees from war-torn nations, Merkel made clear in her notoriously restrained manner.

"The German Chancellor explained that policy to the US President," said her spokesman Steffen Seibert. "She is convinced that the necessary, decisive battle against terrorism does not justify a general suspicion against people of a certain origin or a certain religion."

Already skeptical of Merkel for her close ties to his predecessor, President Barack Obama, Trump as recently as two weeks ago was chastising the German leader for her "very catastrophic mistake ... taking all of these illegals."

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A person familiar with his reaction said the President chafed at Merkel's lecture.

She was only the first in a string of leaders who raised the refugee issue to Trump this weekend. Officials at the White House had booked a full slate of calls, capitalizing on Trump's desire to work long hours and unwillingness to break from his new role. Even when his conversations were meant to occur in the privacy of his own residence, Trump nevertheless dressed in a suit and tie to place the calls from the Oval Office.

But as he began dialing world leaders on Saturday, it became evident that his explosive directive to deny entry to refugees for 120 days, while also banning US travel for all citizens of Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen, would cause problems with his allies.

French President Francois Hollande told Trump that in "an unstable and uncertain world, withdrawal into oneself is a dead-end response," according to a statement from the Élysée Palace.

Hollande, who speaks limited English, told Trump through a translator that democracies could only be defended "if we respect the principles that founded them, especially with the welcoming of refugees."

Australia's Malcolm Turnbull used his phone call to ensure a refugee resettlement agreement signed last year would still be honored. Obama had encouraged Turnbull, a conservative, to develop close ties to Trump in a bid to stabilize the brash new leader.

And May, less than 48 hours after she left the White House, was forced to denounce Trump's policy after British journalists harangued her during a news conference in the Turkish capital Ankara.

"We do not agree with this kind of approach and it is not one we will be taking," a spokesman for May said after her performance at the Turkey news conference was derided. A Downing Street spokesman said May had instructed her foreign and home secretaries to speak with their US counterparts to "protect the rights of British nationals."

Trump is operating without a secretary of state, however, as his nominee Rex Tillerson awaits confirmation by the US Senate. On Saturday he was also operating without his chief liaison to foreign governments, senior adviser Jared Kushner, whose Orthodox Jewish observation of the Sabbath prevents work or the use of technology.

Kushner has assumed an outsized role in the West Wing, principally on foreign affairs, making his absence Saturday notable. Trump, who is also Kushner's father-in-law, has tasked him with managing relations with Mexico amid a dispute over the proposed border wall. He's also regarded by Trump allies in Washington as less ideological than other top advisers, like former Breitbart chairman Steve Bannon or conservative policy stalwart Steven Miller.

Kushner was back in the Oval Office on Sunday as Trump faced a new round of phone calls, plus the news that an American commando had died in a shootout with al Qaeda militants in Yemen . The incident came during the first counterterrorism operation authorized by the new President. Trump, who signed off on the raid last week, nonetheless declared the mission successful in a statement, indicating the US had gathering valuable intelligence, despite the casualty.

"Americans are saddened this morning with news that a life of a heroic service member has been taken in our fight against the evil of radical Islamic terrorism. My deepest thoughts and humblest prayers are with the family of this fallen service member," Trump said in a statement.

Shortly after learning the news, Trump spoke with King Salman of Saudi Arabia, whose military has been battling Houthi militants in Yemen. A Saudi source said the refugee ban was expected to arise on the call.

Trump also spoke with the crown prince of the United Arab Emirates, whose two flagship airlines have faced conflicting guidance in the wake of Trump's order.

Instead of a cluttered nest of papers, Trump's desk on Sunday was neater. After a day of facing withering criticism, both on the phone and in the streets, only a single copy of the New York Post's Inauguration issue lay in front of him, the front page featuring a photo of his swearing-in and the quote "Power to You, the People" from his address.

A few hours after his calls, Trump issued a defiant statement in support of his executive order.

"This is not about religion," he wrote. "This is about terror and keeping our country safe."