Senator John McCain responding to the President's Tweet about Russia.

FOX's Jon Decker has more from the White House:

Senator John McCain and President Trump expressing different views concerning Russia.

The President taking to Twitter, writing:

McCain fired back also on Twitter, writing:

The disagreement coming a day after the President signed a Russia sanctions bill that he said was flawed and clearly unconstitutional.

In Washington, Jon Decker, FOX News.