U.S. President Donald Trump, fresh from a nine-day foreign trip, resumed his media bashing early Sunday. Above, Trump and British Prime Minister Theresa May at a NATO ceremony in Brussels, May 28, 2017. Christian Hartmann/Reuters

U.S. President Donald Trump celebrated his first diplomatic trip abroad Sunday by ramping up complaints against the news media and decrying the lack of post-election coverage of the Montana congressional race that saw a Republican elected the day after he knocked a reporter to the ground, breaking his glasses.

Trump’s only remark on his trip to the Middle East and Europe in an early morning tweetstorm patted himself on the back for the “great success” he achieved.

During his nine-day sojourn, Trump met with leaders in Saudi Arabia, where he made a major speech on the Muslim nations’ role in the fight against terrorism, Israel, the Palestinian Authority and the Group of Seven nations. He also met with the pope at the Vatican.

Read: Congressmen Say President Vulnerable To 'Misinformation And Fake News'

Trump confirmed the U.S. support of NATO but left European leaders guessing on whether he would support the Paris climate agreement.

But on Sunday, Trump resumed his media bashing, calling leaks out of the White House lies, decrying the use of anonymous sources and complaining Greg Gianforte’s special congressional election win Thursday got short shrift.

Trump returned to the United States amid reports his son-in-law and adviser at-large Jared Kushner was under investigation for allegedly attempting to set up back-channel communications with Moscow that would be exempt from U.S. scrutiny.

Read: Clapper Says US Institutions Under Attack — From President

Kushner reportedly made the proposal to Russian Ambassador Sergey Kislyak in December to discuss Syria strategy and other policy issues. The discussions were to be led by Trump point-man Michael Flynn, who was forced to resign as national security adviser just weeks into the Trump administration for lying about his contacts with Russian officials.

The New York Times said the discussion occurred at Trump Tower in New York but was not acknowledged by the Trump transition team at the time.

The Washington Post reported the Russians were surprised by the suggestion because it would have involved using Russian communications equipment. The proposal was transmitted to Moscow on a channel monitored by the U.S.

Kushner has said he doesn’t remember the meeting.

Sen. Lindsey Graham, R-S.C., no fan of the president, said on CNN’s “State of the Union” the allegations should be investigated but he doesn’t put too much stock in them, saying they could be an attempt by the Russians to plant disinformation.

“I think it makes no sense that the Russian ambassador would report back to Moscow on a channel that he most likely knows we’re monitoring,” Graham said. “The whole story line is suspicious.”

The FBI has opened an investigation.

Former Director of National Intelligence James Clapper said he was very concerned about Kushner’s approach to the Russians.

“I will tell you that my dashboard warning light was clearly on, and I think that was the case with all of us in the intelligence community – very concerned about the nature of these approaches to the Russians,” Clapper said on NBC’s “Meet the Press.”

In Montana, Republican Greg Gianforte defeated Democrat Rob Quist in a special election for the House seat vacated by Interior Secretary Ryan Zinke. In his victory speech, Gianforte apologized to Guardian reporter Bob Jacobs for “body-slamming” him when he attempted to ask a question about Gianforte’s position on the Republican health care bill.