Sen. John McCain (R-Ariz.) spent a few hours of his Memorial Day in Syria, meeting with rebel leaders who are trying to topple Syrian President Bashar al-Assad. McCain, the Senate's most prominent supporter of greater U.S. intervention in Syria's civil war, snuck into the country from Turkey. He's the highest-ranking American to visit Syria during the two-year-old conflict.

McCain's visit to Syria was kept secret until he was back in Turkey, at which point The Daily Beast's Josh Rogin published an article on the covert trip. McCain's office then confirmed it. How under-the-radar was the excursion?

McCain's detour was coordinated by the U.S.-based Syrian Emergency Task Force, a nonprofit group that supports the Syrian rebels. Two of the organization's top leaders accompanied McCain, as did Gen. Salem Idris, the leader of the Supreme Military Council of the Free Syrian Army (FSA). Rebel leaders from around the country gathered to meet with McCain and Idris.

Since early April, the U.S. has been providing some Syrian rebels with body armor and night-vision glasses, along with food and medical aid. The Daily Beast's Rogin says the rebels asked McCain for weapons and other military aid. Idris tells Rogin:

We need American help to have change on the ground; we are now in a very critical situation.... What we want from the U.S. government is to take the decision to support the Syrian revolution with weapons and ammunition, anti-tank missiles and anti-aircraft weapons.... Of course we want a no-fly zone and we ask for strategic strikes against Hezbollah both inside Lebanon and inside Syria. [Daily Beast]

The last items on Idris' wish list seem unlikely, at least for now, but as the Syrian war starts spreading into neighboring Lebanon, giving the rebels weapons isn't far-fetched. The European Union late Monday lifted its embargo on arming the opposition, and the Senate Foreign Relations Committee voted last week to arm and provide military training to vetted anti-Assad factions.

Still, President Obama is less than enthusiastic about entangling the U.S. in Syria's civil war. As McCain was meeting with rebel leaders, Secretary of State John Kerry was flying to Paris to work on proposed Syrian peace talks with Russian Foreign Minister Sergey Lavrov, whose government is Assad's biggest backer outside the region. (Rebel leaders reportedly told McCain that there are a growing number of Russian military advisers in Damascus.)

The Obama administration is right to tread carefully, says Patrick Brennan at National Review. Gen. Idris, "a defector from Assad's army who has won fans in the West by rejecting the most extreme and jihadist elements of the opposition," is better than the other anti-Assad forces, notably the radical Islamists of the Nusrah Front. But Idris, "unfortunately, appears to have very little influence or credibility among the rebels," and it's not clear McCain's proposed U.S. military aid would change that, Brennan says.

For now, the U.S. is facilitating the flow of arms from Gulf nations, especially Qatar, to the rebel groups, attempting to keep the weapons out of undesirables' hands. How well that's working is anyone's guess for now, but it's clear that those undesirables, whom Idris has been picked to sideline and provide an alternative to, are the most effective fighters in Syria. They're actually doing a good business in recruiting fighters from the umbrella Free Syrian Army — that's the group Idris is supposed to run some day, and presumably Senator McCain believes he could do so with hundreds of millions of American dollars to fund and control them. Since the fighting has recently intensified and Assad's forces, with Hezbollah and direct Iranian aid at their backs, seem to be winning back some territory, it will be not a surprise if there are increased calls for supporting a leader such as Idris, and whatever troops he can attract, but on the ground in Syria, the credibility and importance of the most effective fighting forces — jihadists — will keep growing. [National Review]

The "optimal geopolitical result" for the U.S. in Syria would be a stalemate, says Paul Mirengoff at Power Line. But the Syrian government appears to be breaking the deadlock, with the help of Hezbollah, and "the revival of Assad's fortunes makes me think that U.S. non-involvement should no longer be considered our best option."

If we were to rank the three possible outcomes of the Syrian civil war — Assad/Hezbollah wins; the rebels win; no one wins — a victory by Assad/Hezbollah would finish third.... Will President Obama provide any support to opposition forces? He is said to be considering it, and continued reports of use of chemical weapons by the regime — which crosses Obama's famous "red line" — could provide the pretext for a shift in course.... For the U.S., there are no good options in Syria. But at this juncture, helping the rebels avoid defeat in Qusair and other key fronts may be the best of the bad ones. [Power Line]

Whatever the best course for America in Syria, McCain's not the person to decide, says Peter Z. Scheer at TruthDig. "By law, senators are not allowed to make foreign policy during their trips abroad, which are meant to be fact finding in nature." And McCain's clandestine sojourn has already upstaged the high-profile negotiations between "the actual secretary of state" and his Russian counterpart.

Worse, McCain "is playing the role of maverick in the most dangerous sense of the word, and may end up forcing the United States into a protracted land war in Syria that it can't easily win," says Will Stabley at the Stabley Times. Somebody may need to "tap Sen. McCain on the shoulder and remind him that he lost the election in 2008 and is in fact not the president."

By traveling to wartorn Syria on his own, [McCain] risks getting attacked by the Syrian army in a manner which would force the United States to respond in kind, dragging our nation into a land war whose results are anything but predictable. And by holding a diplomatic meeting with Syrian rebels, McCain risks antagonizing Syrian leader Assad such that he might in turn feel compelled to attack U.S. interests in the region. After all, a high ranking member of the U.S. government just met with those who are attempting to overthrow him, even if he didn't have the authorization of the U.S. president.

Senator McCain has every right to oppose President Obama's policies toward Syria, as loudly and publicly as he deems necessary. But in meeting with Syrian rebels, he's purposely set off a chain of events which may force the United States in a war with Syria. Nowhere in the Constitution is an individual senator given the power to single-handedly declare war. [Stabley Times]

McCain has done a bit of freelance diplomacy in the past, though. He visited with Libyan rebels before the U.S. and its European allies provided weapons and air support that led to the overthrow and death of Libyan leader Moammar Gadhafi — and eventually, the Benghazi attack that killed U.S. Ambassador Chris Stevens. And, as McCain himself told us, he met with Gadhafi, too.

Sen. Lindsey Graham (R-S.C.) agrees with McCain about Syria, but he apparently feels a little levity is called for regarding McCain's covert day trip:

Before his trip, McCain got in a heated argument with Egyptian veteran diplomat Amr Moussa at the World Economic Forum in Jordan. Watch: