PARIS -- Laying out clear conditions, President Barack Obama and Western allies opened a pathway for Russia to ease tensions in Ukraine on Thursday but pointedly warned Moscow it could face new sanctions within weeks if Vladimir Putin fails to go along.
The leaders, who were gathered in Brussels for a wealthy-nations summit, said the Russian president could avoid tougher penalties in part by recognizing the legitimacy of the new Ukrainian government and ending support for an insurgency in eastern cities that is widely believed to be backed by the Kremlin. There was no mention of rolling back Russia's annexation of the Ukrainian region of Crimea, which precipitated the European crisis.
"We are at a point where Mr. Putin has the chance to get back into a lane of international law," Obama said during a news conference with British Prime Minister David Cameron. But Obama also said the West "can't simply allow drift" in Ukraine, where insurgents continue to clash with government forces in eastern cities.
From Brussels, Obama and other leaders jetted to France ahead of events marking Friday's 70th anniversary of the D-Day Normandy invasion that paved the way for the Allied victory in World War II.
This time Putin was on the scene. And Cameron, French President Francois Hollande and German Chancellor Angela Merkel each were using the commemorations as a backdrop for separate meetings with the Russian president, who arrived in Paris.
Hollande in particular appeared to be embracing the diplomatic mantle, hosting Putin at Elysee Palace Thursday night just after finishing dinner with Obama at a Paris restaurant.
The willingness of Western leaders to meet face-to-face with Putin for the first time since he annexed the Crimean Peninsula from Ukraine marked a noticeable shift in tactics. While leaders have spoken with Putin by phone during the crisis, they had avoided meeting him in person and boycotted the summit he was to host in Russia this week, choosing instead to meet without him in Brussels.
It was the group's first similar summit in two decades without the participation of Russia.
Obama was not scheduled to hold a formal meeting with Putin, though the two men were expected to have some contact at a leaders lunch Friday in Normandy. Secretary of State John Kerry and Russian Foreign Minister Sergey Lavrov, who have met frequently during the crisis, huddled in the French capital Thursday evening.
Aides said Obama was pressing Hollande, Cameron and Merkel to outline for Putin the specific conditions he would have to meet in order to avoid more sanctions. The West wants Putin to recognize the results of Ukraine's May 25 election and start a dialogue with President-elect Petro Poroshenko, end support for the pro-Russian insurgency in eastern Ukraine and stop the flow of arms across the Russian border.
Western leaders voiced some cautious optimism that Putin may be shifting his view of the situation, noting that he did not reject the results of Ukraine's elections outright, nor was there any overt Russian interference in the voting. But with violence still raging near Russia's border with Ukraine, it remained unclear whether Putin was ready to fully de-escalate the months-long crisis or whether the West's threat of more sanctions could push him in that direction.
The U.S. and the European Union already have imposed sanctions on businesses and individuals with ties to Putin. But they have stopped short of slapping harsher penalties on Russia's key economic sectors, including its energy industry.
If there is no change in Russia's involvement in Ukraine, the leaders warned, more sanctions could come within weeks, possibly by the time the European Council meets in late June. But it was unclear whether the West would simply expand the targeted sanctions or move to sector penalties.
Cameron took the most aggressive stance, calling for sector sanctions unless Putin quickly changes his actions.
"The status quo is unacceptable," Cameron declared before his meeting with the Russian leader.
Britain and the U.S. have been the leading advocates for more aggressive penalties, while France and Germany continue to be more reluctant. In a nod to the concerns of the latter nations, which have deep economic ties with Russia, Obama took a softer public line than Cameron, saying, "It's important to take individual countries' sensitivities in mind and make sure that everybody is ponying up."
But he added in regard to further sanctions: "My hope is, is that we don't have to exercise them because Mr. Putin's made some better decisions."
Putin's first opportunity could come as early as Friday, when he and the new Ukrainian president both attend the Normandy events commemorating the D-Day invasion that helped wrest Western Europe from Hitler's grip.
As of Thursday evening, there were no plans for Putin and Poroshenko to hold a formal meeting. White House officials said the Russian leader would need to do more than simply have contact with Poroshenko and would instead have to start substantive talks about the future relationship between the two countries.
Russia has signaled its readiness for a direct dialogue with Poroshenko, a billionaire candy tycoon who will be sworn in on Saturday, but Putin has yet to formally recognize his election.
Poroshenko replaces pro-Moscow President Viktor Yanukovych, who was chased from office three months ago by crowds amid street protests and allegations of corruption. In the wake of Yanukovych's ouster, Russia has annexed Crimea, the eastern regions of Luhansk and Donetsk have declared their independence from Kiev, and the interim Ukrainian government has launched an offensive in the east to oppose an uprising that has left dozens dead.