THE HAGUE, Netherlands » Seeking to isolate Russia, the U.S. and Western allies declared Monday they are indefinitely cutting Moscow out of a major international coalition and warned that they stand ready to order tougher economic penalties if Vladimir Putin presses further into Ukraine.

The moves came amid a flurry of diplomatic jockeying as the West grappled for ways to punish Russia for its annexation of the Crimean Peninsula and prevent the crisis from escalating.

President Barack Obama and the leaders of Britain, France, Germany, Italy, Canada and Japan met in the Netherlands for an emergency meeting of the Group of Seven. In a joint statement after their 90-minute meeting, the leaders said they were suspending their participation with Russia in the Group of Eight major industrial nations until Moscow "changes course."

The G-7 leaders instead plan to meet this summer in Brussels, symbolically gathering in the headquarters city of the European Union and NATO, two Western organizations seeking to bolster ties with Ukraine.

"Today, we reaffirm that Russia’s actions will have significant consequences," the leaders’ statement said. "This clear violation of international law is a serious challenge to the rule of law around the world and should be a concern for all nations."

In an unexpected development, Russia’s foreign minister Sergey Lavrov met separately in The Hague with his Ukrainian counterpart, the highest level of contact between the two nations since Russia moved forces into Crimea nearly a month ago. U.S. officials said they welcomed the meeting but challenged Russia to take further steps to de-escalate the conflict.

Lavrov sought to downplay the significant of the West purging Russia from the G-8, describing the economic partnership as an informal club that has been superseded by other international forums.

"If our Western partners believe that such format is no longer needed, let it be so," Lavrov said. "We aren’t clinging for that format, and we won’t see a big problem if there are no such meetings for a year, or a year-and-half."

Russia’s actions have sparked one of Europe’s deepest political crises in decades and drawn comparisons to the Cold War era’s tensions between East and West. Obama and other Western leaders have condemned Russia’s movements and ordered economic sanctions on Putin’s close associates, though those punishments appear to have done little to change the Russian president’s calculus.

Hours before world leaders began meeting in The Hague, Russian forces stormed a Ukrainian military base in Crimea, the third such action in as many days. Ukraine’s fledgling government responded by ordering its troops to pull back from the strategically important peninsula.

In Washington, meanwhile, the Senate moved past a procedural hurdle and toward a vote, possibly late this week, on Russia sanctions and Ukraine aid. In New York, Ukraine pushed for the United Nations General Assembly to adopt a resolution this week reaffirming the country’s territorial integrity and declaring that the referendum in Crimea that led to its annexation by Russia "has no validity."

In the Hague, the G-7 leaders also discussed plans for increasing financial assistance to Ukraine’s central government. And they vowed to launch coordinated sanctions on key sectors of the Russian economy if Putin presses into areas of southern and eastern Ukraine.

Among the sectors that could be targeted are Russia’s robust energy industry, as well as its banking and defense industries.

U.S. officials said Obama had managed to win support for those potentially bruising sanctions from European leaders, who have been wary of the boomerang impact such penalties could have on their own economies. Russia is one of the European Union’s largest trading partners and supplies the continent with significant energy resources.

Officials said the leaders agreed that while energy sanctions could have a negative impact on the global economy, the consequences would be worse for Russia. The leaders also agreed that there were risks in not taking tougher measures, particularly if Russia escalates its incursion elsewhere in the region, officials said.

In another attempt to alienate Russia from the international community, Obama held a separate meeting Monday with Chinese President Xi Jinping, whose country frequently sides with Moscow in disputes with the West.

The U.S. has been appealing to China’s vehement opposition to outside intervention in other nations’ domestic affairs and scored a symbolic diplomatic gain when Beijing abstained a week ago from voting on a United Nations Security Council resolution declaring Crimea’s secession referendum illegal. With Russia vetoing the measure and the 13 other council members voting in favor, China’s abstention served to isolate Moscow internationally.

"I believe ultimately that by working together, China and the United States can help strengthen international law and respect for the sovereignty of nations and establish the kind of rules internationally that allow all peoples to thrive," Obama said while standing alongside Xi ahead of their hour-long meeting.

In a counterpoint to Obama and his G-7 partners, a group of five major emerging economies — Brazil, Russia, India, China and South Africa — issued a statement Monday opposing sanctions and urging nations to work through the U.N. instead. The so-called BRICS nations said hostile language, sanctions and force do not "contribute to a sustainable and peaceful solution."

The scheduled purpose for Obama’s long-planned trip to the Netherlands was the two-day Nuclear Security Summit, an international forum the president created during his first term that focuses on eliminating or securing the world’s nuclear materials. While the nuclear talks were overshadowed by the dispute with Russia, Obama did score a key victory on that front Monday when Japan announced that it was turning over to the U.S. a portion of its weapons-grade plutonium and highly-enriched uranium stockpiles.

Obama arrived in the Netherlands Monday morning after an overnight flight from Washington. He opened his visit with a stop at Amsterdam’s Rijksmuseum, where he admired Rembrandt’s massive 17th-century painting "Night Watch."

The president’s weeklong trip also includes stops in Brussels, where he’ll meet with European Union leaders, and Rome, where he’ll have an audience with Pope Francis. He’ll close his trip in Saudi Arabia, a visit aimed at soothing tensions with a key Gulf ally.