Sen. John McCain (R-Ariz.), the Senate Armed Forces Committee's top Republican, pressured the White House on Monday to decide whether or not to send more troops to Afghanistan.

It was reported Monday that the top U.S. and NATO commander in Afghanistan, Gen. Stanley McChrystal, requested that the Pentagon send additional forces to the war-torn country. McChrystal's recommendation came in his long-awaited report on the state of the conflict between allied units and insurgents.

The Arizona Republican, who has long favored sending more troops, Tweeted:

General McChrystal: "More troops or Mission Failure." — we need a decision now.

McCain borrowed the headline of a Washington Post story that broke the news of the McChrystal report.

When he was the GOP's presidential nominee last year, McCain advocated for a "surge" in Afghanistan similar to the strategy undertaken by Gen. David Petraeus in Iraq.

It is unclear if Congress will approve additional troops. Senate Armed Forces Committee Chairman Carl Levin (D-Mich.) and House Speaker Nancy Pelosi (D-Calif.) have both balked at the move. But Levin said on Sunday that the decision would ultimately be up to the president.