President Donald Trump on Monday took fresh aim at Amazon.com Inc., as he tweeted that he gave up “nothing” in his meeting with Russian President Vladimir Putin and was considering revoking security clearances for former officials who have been critical of him.

AMAZON AND ANTITRUST

Trump took his latest swipe at Amazon AMZN, +0.66% for “using” the U.S. Postal Service as its “delivery boy” and raised the possibility of bringing antitrust claims against the company. In a series of tweets, Trump railed against Amazon and the Washington Post, which is owned by Amazon CEO Jeff Bezos. Shares of Amazon fell nearly 2% in early trading before paring losses.

“In my opinion the Washington Post is nothing more than an expensive (the paper loses a fortune) lobbyist for Amazon. Is it used as protection against antitrust claims which many feel should be brought?” Trump said. He did not elaborate on any antitrust matters. Trump has frequently targeted Amazon for what he says is the company’s being subsidized by the Postal Service.

Also read:Amazon earnings: Prime Day isn’t the only thing giving business a boost.

‘VERY HAPPY!’

Trump also took issue with a Washington Post report that he is privately frustrated with how talks with North Korea are proceeding.

“The Fake News is saying, without ever asking me (always anonymous sources), that I am angry because it is not going fast enough. Wrong, very happy!” he tweeted.

Trump also spoke briefly on Iran as he toured a “Made in America” exhibition on the South Lawn, saying “none at all,” when asked if he had concerns about provoking tensions with the country. Sunday, the president tweeted a warning to the country’s president, Hassan Rouhani, saying there would be consequences if Iran threatens the U.S.

Read:Trump tweets all-caps tirade warning Iran never to threaten U.S.

‘EXPLORING’ REVOKING CLEARANCES

Trump’s press secretary Sarah Sanders said the president is “exploring the mechanisms” to take away security clearances from former CIA director John Brennan, ex-FBI chief James Comey, former national intelligence director James Clapper, and others who have been critical of his presidency. The statement from Sanders came after Sen. Rand Paul, a Kentucky Republican, met with Trump and asked for Brennan’s clearance to be revoked. The ex-CIA chief said last week that Trump’s news conference with Putin was “nothing short of treasonous.”

CNN says former intelligence officials typically keep high-level security clearances after they leave their posts. Sanders said Trump is also considering revoking the clearances of former National Security Agency Director Michael Hayden, former national security adviser Susan Rice and former FBI Deputy Director Andrew McCabe. Sanders said the officials have “politicized and in some cases monetized their public service and security clearances.”

TRUMP SAYS HE GAVE UP ‘NOTHING’ WITH PUTIN

As he continues to face criticism of his meeting with Putin, Trump tweeted that he “gave up NOTHING” during their summit last week.

“We merely talked about future benefits for both countries,” Trump said. Trump has faced criticism for publicly doubting the conclusion of U.S. intelligence agencies about Russian election interference. Trump later sought to walk that statement back.

Also see:Kissinger talks Helsinki, Putin, Trump, AI and more over lunch with the FT