"Leaking, and even illegal classified leaking, has been a big problem in Washington for years," Trump tweeted.
"'Failing' New York Times and other publications 'must apologise'!" the US President demanded.
In a series of tweets, Trump attacked the mainstream American media for being unfairly critical of him and his policies.
"The spotlight has finally been put on the low-life leakers! They will be caught!" he said.
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Since his campaign, the US President has been attacking the mainstream American media.
At times, he even denied credentials to some of the top US dailies like The Washington Post and called CNN as Clinton News Network.
He alleged that the Democrats who lost the presidential elections in November are now blaming the alleged Russian involvement for their defeat.
"The Democrats had to come up with a story as to why they lost the election, and so badly (306), so they made up a story - RUSSIA. Fake news!" Trump said.
"Stock market hits new high with longest winning streak in decades. Great level of confidence and optimism - even before tax plan rollout!" he said.
The renewed focus on tracking down leaks comes following National Security Adviser Michael Flynn's resignation amid reports he misled Vice President Pence about a phone call with a Russian diplomat. Flynn's alleged deception was revealed by leaks.
While Trump apparently sought Flynn's resignation, the episode swiftly rekindled the president's feud with the intelligence community.