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President Barack Obama arrives in Europe later Monday for G-7 and E.U. meetings expected to be overshadowed by Russia’s annexation of Crimea and the threat of further Russian incursions into Ukraine.

As Russia tightens its grip on Crimea and continues to deploy and position its military might, the United States and the European Union hope to forestall any new Russian advances.

Obama addressed the situation earlier in the week.

“The world is watching with grave concern as Russia has positioned its military in a way that could lead to further incursions into southern and eastern Ukraine," he said.

"For this reason, we have been working with our European partners to develop more severe actions that could be taken if Russia continues to escalate the situation,” he added.

According to National Security Advisor Susan Rice, the administration is leaving no doubt as to the focus of this week’s consultations.

"These meetings obviously take place against the backdrop of Russia’s intervention in Ukraine. What will be clear for the entire world to see is that Russia is increasingly isolated,” said Rice.

With an overwhelming Russian force massed along its eastern borders, Ukraine is bracing for further incursions.

Ukraine's acting Foreign Minister Andri? Deshchytsia said that his country is trying to exercise retraint.

"The Ukrainian government is trying to use all peaceful and diplomatic means to stop Russia. At this moment, when Russian troops would be invading Ukraine from the east, it would be difficult for us to ask Ukrainians who are living there not to respond to a military invasion,” he said.

Last week, the United States tightened sanctions against Russia. Moscow responded with travel bans on high-ranking U.S. officials and lawmakers, including Senator John McCain, who is urging a boost in U.S. assistance to Kyiv.

"I see nothing wrong with providing both lethal and non-lethal assistance to the government of Ukraine which has just had its nation invaded and dismembered," he said.

The crisis in Ukraine is sure to also be a focal point of deliberations on Capitol Hill when lawmakers return from a weeklong recess Monday.