Arizona Sen. John McCain, a Russia hawk and occasional Donald Trump critic, blasted a report on the administration's new Syria posture just hours after revealing he had a cancerous brain tumor.

McCain's statement faulted the administration for reportedly ending a covert program begun during the Obama administration to provide arms to Syrian rebels battling President Bashar al-Assad.

'If these reports are true, the administration is playing right into the hands of Vladimir Putin,' the Armed Services Committee chairman said in a statement.

Senator McCain blasted a report on the administration's new Syria posture just hours after revealing he had a cancerous brain tumor

The statement served as a reminder that so long as he is in the Senate, McCain will continue to warn against the administration's proposed move toward Moscow.

The former Vietnam POW also thanked the collection of supporters who sent their encouragement after he revealed the life-threatening diagnosis that was discovered.

"I greatly appreciate the outpouring of support - unfortunately for my sparring partners in Congress, I'll be back soon, so stand-by!" McCain wrote on Twitter.

Close McCain friend Sen. Lindsey Graham of South Carolina said McCain called him three times today seeking updates on his work.

'"No more woe is me." He is yelling at me to buck up. I'm going to buck up,' said Graham, who said on the initial news of his longtime pal's diagnosis that cancer was in for a real fight from McCain.

Senator John McCain was diagnosed with a malignant primary brain tumor after being hospitalized for a blood clot just behind his left eye

The 80-year-old Rep. Senator for Arizona underwent surgery last week for what was thought to be a blood clot above his eye. On Wednesday, McCain's family revealed that after the surgery, doctors discovered cancerous tissue in his brain.

'On Friday, July 14, Sen. John McCain underwent a procedure to remove a blood clot from above his left eye at Mayo Clinic Hospital in Phoenix,' according to a statement. 'Subsequent tissue pathology revealed that a primary brain tumor known as a glioblastoma was associated with the blood clot,' the family said in a statement.'

The average life span for someone with a glioblastoma is 14 to 16 months after diagnosis.

McCain's statement also blasted the Trump administration for failing to put forth a Syria strategy.

'Making any concession to Russia, absent a broader strategy for Syria, is irresponsible and short-sighted,' he said.

Glioblastoma is the most aggressive tumor that can form in the brain. Patients have a 10 percent chance of surviving five years after their diagnosis

President Donald Trump speaks at a luncheon with GOP leadership, Wednesday, July 19, 2017, in the State Dinning Room of the White House in Washington. He is ending a covert CIA program to arm Syrian rebels

'The administration has yet to articulate its vision for Syria beyond the defeat of ISIL, let alone a comprehensive approach to the Middle East. A key pillar of American strategy must be the removal of Assad from power as part of an end to the brutal conflict in Syria, which has fueled ISIL’s growth through its cruelty, extended malign Iranian influence, and undermined broader regional stability,' he said.

'Six months into this administration, there is still no new strategy for victory in Afghanistan either. It is now mid-July, when the administration promised to deliver that strategy to Congress, and we are still waiting,' he said.

Trump is reportedly ending a covert CIA program that delivered arms to Syrian rebels - a program that was mocked as illegal by Russian President Vladimir Putin.

The program sought to identify a moderate opposition, delivering arms as a way to put pressure on Syrian dictator Bashar al-Assad.

It was begun in 2013 during the Obama administration.

The president decided to end it a month ago following a meeting with CIA Director Mike Pompeo and national security advisor H.R. McMaster, the Washington Post reported.

In doing so, the Trump administration was yielding to a key demand of Moscow, which dispatched troops in 2015 to pro up the Assad regime, which fought back against rebels with a ruthless campaign of attacks using its helicopters and other means.

'If true – and I hope it’s not – it would be a complete capitulation to Assad, Russia, and Iran,' wrote South Carolina Sen. Lindsey Graham on Twitter this week when the news broke

Officials said the pull-back was part of Trump's effort to seek improved ties with Moscow, and and acknowledgement that it was unlikely to succeed now that Assad has consolidated power, aided by support from Russia's air force.

Putin blasted the U.S. program in 2015 as illegal in advance of a meeting with Obama.

'In my view, providing military aid to illegitimate organizations contravenes the principles of international law and the U.N. Charter,' Putin said. 'We back only legal government entities.' He said the only legitimate army was that controlled by Assad.

The 80-year-old's daughter, Fox News host Meghan, shared an emotional message after the news emerged on Wednesday night. The pair are pictured at the 2013 White House Correspondents' Dinner

Putin blasted the U.S. program in 2015 as illegal in advance of a meeting with President Obama, who authorized it in 2013

Smoke rises from buildings after Assad Regime's forces hit de-conflict zone of opposition controlled Ein Terma region in Damascus, Syria on July 18, 2017. (Photo by Qusay Nour/Anadolu Agency/Getty Images)

Smoke rises from the Syrian town of Kobani, seen from near the Mursitpinar border crossing on the Turkish-Syrian border in the southeastern town of Suruc in Sanliurfa province on October 12, 2014 in Sanliurfa, Turkey. Kurdish forces defending Kobani urged a U.S.-led coalition to escalate air strikes on Islamic State fighters who tightened their grip on the Syrian town at the border with Turkey

People are silhouetted on the top of a hill close to the border line between Turkey and Syria near Mursitpinar bordergate as they watch the U.S led airstrikes over ther Syrian town of Kobani on October 19, 2014. Kurdish fighters in Syrian city of Kobani pushed back Islamic State militants in a number of locations as U.S. air strikes on ISIS positions continue in and around the city

The covert program was intended to weaken Syrian President Bashar al-Assad

The decision was made last month after an Oval Office meeting that included CIA Director Mike Pompeo, the Washington Post reported

Trump has repeatedly pushed for negotiations and improved relations with Russia. Following a bilateral meeting between the two presidents in Hamburg, Trump touted a recent cease fire over part of Syria that has held for several days.

On Tuesday night, the White House confirmed that Trump and Putin held a second, previously undisclosed meeting during a G20 dinner.

The New York Times reported that the meeting lasted an hour, but the White House said it was brief.