United States Ambassador to the United Nations Samantha Power ripped into Russia's government during an emergency meeting of the U.N. Security Council on Monday on the Ukrainian crisis.

Power accused Russia of an act of aggression, not a humanitarian mission. She said there was nothing to justify its conduct in escalating military operations in the Crimea region of Ukraine after the ouster of former Ukrainian President Viktor Yanukovych, an ally of the Russian government of President Vladimir Putin.

"Russia has every right to wish events had turned out differently. It doesn't have the right to express that using military force," Power said.

Power said there is no evidence of any threats to Russian citizens or ethnic Russians in the Crimean peninsula, after Russia's ambassador to the U.N. had suggested Russians are "being persecuted for ideas and language."

"Russian mobilization is in response to an imaginary threat," she said.

Power called for a deployment of human-rights monitors in Ukraine, and called on Russia to "immediately pull back" its forces.

U.S. President Barack Obama said Russia was "on the wrong side of history" in Ukraine on Monday, and warned of potential diplomatic and economic "isolation."

Here is the full text of Power's remarks at the U.N.:

Thank you Madam President. Listening to the representative of Russia, one might think that Moscow had just become the rapid response arm of the Office of the High Commissioner for Human Rights. So many of the assertions made this afternoon by the Russian Federation are without basis in reality.

Let’s begin with a clear and candid assessment of the facts.

It is a fact that Russian military forces have taken over Ukrainian border posts. It is a fact that Russia has taken over the ferry terminal in Kerch. It is a fact that Russian ships are moving in and around Sevastapol. It is a fact that Russian forces are blocking mobile telephone services in some areas. It is a fact that Russia has surrounded or taken over practically all Ukrainian military facilities in Crimea. It is a fact that today Russian jets entered Ukrainian airspace. It is also a fact that independent journalists continue to report that there is no evidence of violence against Russian or pro-Russian communities.

Russian military action is not a human rights protection mission. It is a violation of international law and a violation of the sovereignty and territorial integrity of the independent nation of Ukraine, and a breach of Russia’s Helsinki Commitments and its UN obligations.

The central issue is whether the recent change of government in Ukraine constitutes a danger to Russia’s legitimate interests of such a nature and extent that Russia is justified in intervening militarily in Ukraine, seizing control of public facilities, and issuing military ultimatums to elements of the Ukrainian military. The answer, of course, is no. Russian military bases in Ukraine are secure. The new government in Kyiv has pledged to honor all of its existing international agreements, including those covering Russian bases. Russian mobilization is a response to an imaginary threat.

A second issue is whether the population of the Crimea or other parts of eastern Ukraine, are at risk because of the new government. There is no evidence of this. Military action cannot be justified on the basis of threats that haven’t been made and aren’t being carried out. There is no evidence, for example, that churches in Eastern Ukraine are being or will be attacked; the allegation is without basis. There is no evidence that ethnic Russians are in danger. On the contrary, the new Ukrainian government has placed a priority on internal reconciliation and political inclusivity. President Turchinov – the acting President – has made clear his opposition to any restriction on the use of the Russian tongue.

No one has to explain to Ukraine’s new government the need to have open communications, not only with leaders of the country’s Russian ethnic minority in the Crimea and elsewhere, but also with its neighbors. That is why, when the current crisis began, the government sent its former Chief of Defense to the region to try to defuse the situation. A second emissary was prevented from entering the Crimean Rada to engage in discussions. And it is why Ukrainian authorities have repeatedly reached out to Russia. Russia needs to reciprocate and begin to engage directly with the Government of Ukraine.

I note that Russia has implied a right to take military action in the Crimea if invited to do so by the prime minister of Crimea. As the Government of Russia well knows, this has no legal basis. The prohibition on the use of force would be rendered moot were sub-national authorities able to unilaterally invite military intervention by a neighboring state. Under the Ukrainian constitution, only the Ukrainian Rada can approve the presence of foreign troops.

If we are concerned about the rights of Russian-speaking minorities, the United States is prepared to work with Russia and this Council to protect them. We have proposed and wholeheartedly support the immediate deployment of international observers and monitors from the UN or OSCE to ensure that the people about whom Russia expresses such concern are protected from abuse and to elucidate for the world the facts on the ground. The solution to this crisis is not difficult to envision. There is a way out. And that is through direct and immediate dialogue by Russia with the Government of Ukraine, the immediate pull-back of Russia’s military forces, the restoration of Ukraine’s territorial integrity, and the urgent deployment of observers and human rights monitors, not through more threats and more distortions.

Tonight the OSCE will begin deploying monitors to Ukraine. These monitors can provide neutral and needed assessments of the situation on the ground. Their presence is urgently necessary in Crimea and in key cities in eastern Ukraine. The United States calls upon Russia to ensure that their access is not impeded.

The leadership in Moscow may well be unhappy about former President Yanukovych’s decision to flee Ukraine and move in with them. Russia may be displeased with the new government, which was approved by Ukraine’s parliament by an overwhelming majority, including members of Yanukovych’s own party. Russia has every right to wish that events in Ukraine had turned out differently, but it does not have the right to express that unhappiness by using military force or by trying to convince the world community that up is down and black is white. Russia’s calls to turn back time to implement the February 21 Agreement ring hollow. It was Yanukovych who failed to abide by the terms of that agreement, fleeing Kyiv, and ultimately Ukraine.

The United States categorically rejects the notion that the new Government of Ukraine is a “government of victors.” It is a government of the people and it is one that intends to shepherd the country toward democratic elections on May 25th – elections that would allow Ukrainians who would prefer different leadership to have their views heard. And the United States will stand strongly and proudly with the people of Ukraine as they chart out their own destiny, their own government, their own future.

The bottom line is that, for all of the self-serving rhetoric we have heard from Russian officials in recent days, there is nothing that justifies Russian conduct. As I said in our last session, Russia’s actions speak much louder than its words. What is happening today is not a human rights protection mission and it is not a consensual intervention. What is happening today is a dangerous military intervention in Ukraine. It is an act of aggression. It must stop. This is a choice for Russia. Diplomacy can serve Russia’s interests. The world is speaking out against the use of military threats and the use of force. Ukrainians must be allowed to determine their own destiny. Thank you Madam President.