WASHINGTON -- Hours after returning from his first trip abroad as president, President Trump tweeted Sunday about "fake news media" and White House leaks.

"It is my opinion that many of the leaks coming out of the White House are fabricated lies made up by the #FakeNews media," Mr. Trump said in a series of tweets.

"Whenever you see the words 'sources say' in the fake news media, and they don't mention names... it is very possible that those sources don't exist but are made up by fake news writers. #FakeNews is the enemy!" he tweeted.

It is my opinion that many of the leaks coming out of the White House are fabricated lies made up by the #FakeNews media. — Donald J. Trump (@realDonaldTrump) May 28, 2017

Whenever you see the words 'sources say' in the fake news media, and they don't mention names.... — Donald J. Trump (@realDonaldTrump) May 28, 2017

....it is very possible that those sources don't exist but are made up by fake news writers. #FakeNews is the enemy! — Donald J. Trump (@realDonaldTrump) May 28, 2017

On Sunday night, Mr. Trump followed up by tweeting that the "fake news media" disparges his use of social media "because they don't want America to hear the real story!"

The Fake News Media works hard at disparaging & demeaning my use of social media because they don't want America to hear the real story! — Donald J. Trump (@realDonaldTrump) May 29, 2017

The president unleashed his apparent frustration as he faces a slew of challenges upon returning home from his nine-day trip to Europe and the Middle East.

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His son-in-law and senior adviser, Jared Kushner, is under scrutiny in the FBI's probe into Russian election meddling and the Trump campaign. Reports also say that Kushner proposed that a secret communications channel could be set up between the Trump transition team and Russia.

Earlier this month, reports said that Mr. Trump told Russian diplomats that firing "nut job" FBI Director James Comey relieved "great pressure" on him, and that a senior adviser in his White House is a significant person of interest in the FBI's investigation into Russian election meddling. There were also revelations this month of a memo that Comey wrote that says Mr. Trump asked him to drop an investigation into Michael Flynn.

Seemingly unable to control the leaks within his own White House, Mr. Trump has become increasingly frustrated. CBS News chief White House correspondent Major Garrett reported that administration officials feel the leaks in recent days have been "coordinated and timed." Officials within Mr. Trump's White House believe leaks of Mr. Trump's recent conversation with Russian Foreign Minister Sergey Lavrov are a "deliberate attempt" by former Obama and current officials looking to damage Mr. Trump's presidency.

The president did not hold a press conference during his nine-day trip, leaving top White House aides to give brief remarks and take a few questions. But back home, questions continue to surround the president.

The White House is considering restructuring its communications staff. It is unclear when proposals for changes will be presented to Mr. Trump, but it will likely take place sometime soon, now that the president has returned to Washington.

The president will be presented with proposals to set up messaging teams both inside and outside the White House to handle rapid response on all fronts. The teams will also hone messaging on the Russia probe, CBS News' Steve Chaggaris reported.