A day after using Twitter to tell Russia to "get ready" for U.S. missile attacks on Syria, President Donald Trump on Thursday softened his tone on Thursday morning, raising the possibility that despite his tough warnings from earlier this week, there might be no U.S. military response over the Syrian government's use of chemical weapons, as Pentagon leaders readied options for Mr. Trump.

"We're looking very, very seriously, very closely at that whole situation," the President said to reporters. "We'll see what happens."

Earlier in the day on Twitter, the President seemed to hedge on his vow a day earlier to fire missiles into Syria.

"Never said when an attack on Syria would take place," the President wrote on Twitter early this morning. "Could be very soon or not so soon at all!"

24 hours earlier, the President had been much more definitive, scoffing at the talk of Russian officials that they would stop any U.S. missile attacks on military positions in Syria.

"Get ready Russia, because they will be coming, nice and new and “smart!”" Mr. Trump tweeted.

On Capitol Hill, Defense Secretary James Mattis sidestepped any details of possible plans, as he was asked about Syria repeatedly at a House hearing.

"I do not want to discuss the current situation, because I owe confidentiality to our allies," Mattis said, as the Pentagon chief acknowledged the difficulty in dealing not only with Syria, but Russia as well.

"On a strategic level, it's how do we keep this from escalating out of control," Mattis said. "If you get my drift on that."

On Monday, the President vowed that military decisions on a Syria strike would be made within 24 to 48 hours, as the White House scrapped his planned trip to South America next week to allow him to deal with the Syrian crisis.

That was followed by yesterday's tweet about missiles and Russia.

Democrats in Congress said the tweets demonstrated the Trump Administration wasn't ready for prime time, as Sen. Robert Menendez (D-NJ) called Mr. Trump the "Commander-in-Chaos."

"This is the most solemn and serious decision a President must make, and it’s never been done in such a disorganized and juvenile manner," said Sen. Brian Schatz (D-HI).

There were also a few voices in both parties who called on the President to get the permission of Congress before launching any strike.

"We can’t bomb our way to peace," said Rep. Barbara Lee (D-CA).

"I again implore President Trump to consult with Congress before engaging our armed forces," said Sen. Mike Lee (R-UT).

Those two Lees are not related - and are on opposite sides of the political spectrum - but they represent a small slice of the House and Senate who feel Congress is too often left out of decisions on using U.S. military force.