Updated at 7:30 p.m.

The situation in Ukraine has escalated rapidly over the weekend, with thousands of Russian troops entering Crimea and leaders in the international community announcing their allegiances and planning their next steps as this conflict unfolds. Here is a collection of statements made by leading officials in the United States, Europe and Russia over the weekend.

Two women hold posters during a protest Sunday in Kiev, Ukraine, against Russia's military intervention in Crimea. The poster in the right side reads in Ukrainian: "I am from Russia, please protect me and remove the weapons and soldiers from Ukraine." (Emilio Morenatti/ AP)

Secretary of State John F. Kerry

On "Meet the Press"

The people of Ukraine are fighting for democracy, they're fighting for freedom, they're fighting to have their voices heard and not be governed by a kleptocracy, by a tyrant, by someone who puts their political opposition in jail, somebody who robs the country of its livelihood and future. And they spoke out against snipers from roofs who were killing thing, they kept on marching and fought for their freedom.  Now they have the opportunity for that democracy.  And by the way, President Yanukovych's only supporters abandoned him.  They voted against him.  They impeached him. So Russia and President Putin are aligning themselves firmly with this kleptocracy.  They're aligning themselves with the person who was legitimately stripped of his power by the parliament, even by his own supporters.  I think this is an enormous mistake for Russia

On "This Week with George Stephanopoulos"

We are not looking for a U.S.-Russia, East-West redux here.  What we want is for Russia to work with us, with Ukraine.  If they have legitimate concerns, George, about Russian speaking people in Ukraine, there are plenty of ways to deal with that without invading the country.  They have the ability to work with the government, they could work with us, they could work with the UN.  They could call for observers to be put in the country.  There are all kinds of alternatives.  But Russia has chosen this aggressive act, which really puts in question Russia’s role in the world and Russia’s willingness to be a modern nation and part of the G8.

On "Face the Nation"

I think Russia needs to think very carefully about the choice that it’s making. And there are visa bans, asset freezes, isolation with respect to trade, investment, American businesses may well want to start thinking twice about whether they want to do business with a country that behaves like this. These are serious implications. And I know from my conversations yesterday: everyone of our allies, friends are determined to stay united and to make clear there is a price attached to this kind of behavior.

President Obama

It would be a clear violation of Russia’s commitment to respect the independence and sovereignty and borders of Ukraine, and of international laws. And just days after the world came to Russia for the Olympic games, it would invite the condemnation of nations around the world. And indeed, the United States will stand with the international community in affirming that there will be costs for any military intervention in Ukraine.

President Vladimir Putin's office

In the case of any further spread of violence to Eastern Ukraine and Crime. Russia retains the right to protect its interests and the Russian-speaking population of those areas.

Secretary of Defense Chuck Hagel

I won't get into the different specific options, but this could be a very dangerous situation if this continues in a very provocative way.  We have many options, like any nations do.  We're trying to deal with the diplomatic focus.  That's the appropriate responsible approach and that's what we're going to continue.

Sen. Marco Rubio (R-Fla.)

If you’re asking me whether the U.S. should be taking military strikes against Russian troops in Ukraine or in Crimea, I would argue to you that I don’t think anyone is arguing for that.

Sen. Lindsey O. Graham (R-S.C.)

Stop going on television and trying to threaten thugs and dictators. It is not your strong suit. Every time the president goes on national television and threatens Putin or anyone like Putin, everybody’s eyes roll, including mine. We have a weak and indecisive president that invites aggression. President Obama needs to do something.

Senate Majority Whip Richard J. Durbin (D-Ill.)

We’ve got to remember Putin developed his political finesse as the head of the Soviet secret police, and his idea of invading countries, occupying them and really daring people to go to war, those are the tactics of a bully.

Sen. Rob Portman (R-Ohio)

You look at what is happening in the Ukraine. But also, look beyond Ukraine and look at what is happening in the South China Sea with China. Look at what is happening in the Middle East. We could not have done the surge in Iraq, in my view, with an Army that size. And so, look, this is a problem. And we need to be sure that these changes and the defense budget are consistent with what we need to do around the world, which unfortunately, the United States is still in the position of having to lead around the world to avoid the kind of instability we see right now in Crimea.

Former Sen. Evan Bayh (D-Ind.)

We have three options. You can do symbolic things and threatening to cancel the G-8 meeting or at least withdraw from the preparatory talks is one of those things. But Vladimir Putin won't care about that. You can do some financial things, which George mentioned. If we could get the cooperation of the Europeans, we could really penalize the Russians. But that would require the Europeans to make sacrifices, which historically they've been very reluctant to do. Or perhaps, and more likely, we can look at other spheres of influence that the Russians care about. Syria, for example, and really step up some of our things there to try and replace the Assad regime. But to directly intervene in Ukraine, there is just realistically, not much we can do that the American people are willing to pay the price for.

Former Sen. Scott Brown (R-Mass.)

No one wants another war. When you're looking or speaking to people in just last night I was out and talked to folks. And they say what do you think about what the president is doing with Ukraine? They kind of chuckle because of what we've had and what we've seen with obviously Syria with the red line issues, with Benghazi, with "Fast and Furious," with Obamacare, there is always these empty threats. So there is a problem of credibility. And I don't think Putin really cares what President Obama says or does. ... economic sanctions and economic issues withholding certain opportunities is where you're going to get the best bang for your buck. And we can't do it alone. We need to do it with our European partners.

Samantha Power, U.S. ambassador to the United Nations

Actions speak louder than words.  Early this morning, the Russian Duma acted to authorize the use of military force in Ukraine.  This is as dangerous as it is destabilizing.  We are deeply disturbed by reports this morning of Russian military intervention into Crimea.  This intervention is without legal basis-indeed it violates Russia's commitment to protect the sovereignty, territorial integrity, and independence of Ukraine.  It is time for the Russian intervention in Ukraine to end.

The Russian military must stand down; the aspirations of the Ukrainian people must be respected; and political dialogue must be allowed to continue.  We applaud the remarkable restraint and commitment to that dialogue that the new Ukrainian government in Kyiv has demonstrated in the face of hostility.

House Intelligence Committee Chair Mike Rogers (R-Mich.)

Putin is playing chess, and we are playing marbles.

Oleksandr Turchynov, Ukraine's acting president

They are provoking us into a military conflict. According to our intelligence, they are trying to implement the scenario that is very similar to Abkhazia.

Arseniy Yatsenyuk, Ukraine’s new prime minister 

This is actually a declaration of war to my country ... If he wants to be the president who started the war between two neighboring and friendly countries, he is within just a few inches of his target. We are on the brink of disaster.

Dmitry Medvedev, Prime Minister of Russia

Russia is ready to develop multi-faceted, respectful relations with brotherly Ukraine - mutually beneficial and effective relations ... Russia needs a strong and stable Ukraine. A predictable and economically thriving partner. Not a poor relation that's always standing with a hand held out.

British Foreign Secretary William Hague

In addition to calling yesterday's emergency meeting of the U.N. Security Council, the United Kingdom will join other G-8 countries this week in suspending our co-operation under the G-8, which Russia chairs this year, including the meetings this week for the preparation of the G-8 summit.