This is a CBS news special report on Dave Barrett joined by correspondent Peter Mayer at the White House. But the president is set to speak on the situation in Ukraine. Following the downing of a Malaysian jetliner last Thursday and from Kiev CBS's Kenny McCormick joins us with the latest from Ukraine. As of this morning Ukrainian officials said that 272 bodies and 66 fragments of bodies have been found. But 250 bodies have been placed in refrigerated train cars that train may begin moving in less than an hour. Peter Mayer at the White House what can we expect from the president. Well let's set the stage a first year the scene the president speaking Dave from the area just outside the door to the Oval Office and near the South Lawn. This appearance which until less than an hour ago was not on the president's public schedule comes as the US is. Building its case blaming pro Russian separatists for downing the Malaysian jetliner. The administration is also speaking out about the treatment of the bodies you just mentioned the possible movement of those up boxcars the bodies of the victims and the failure to secure the crash site crime scene. Mr. Obama is also demanding a cease fire in the troubled region of Ukraine we expect that day he'll be talking about that again. Of the world will be watching and listening for what he has to say about Russian involvement and specifically any new demands to Russian President Putin. President Obama now walking it down the yes side walk. To be a microphone here and now is the president of the United States. Warrior by. Wanna make a brief statement about the tragedy in Ukraine. Before I do though I wanna know that secretary Kerry has departed for the Middle East. As I've said many times. Israel has a right to defend itself against rocket and tunnel attacks from Hamas. And as a result of its operations Israel has already done significant damage to hamas'. Terrorist infrastructure in Gaza. I've also said our. That we have serious concerns about the rising number of Palestinian. Civilian deaths and the loss of Israeli lives. And that is why it now has to be our focus and focusing international community. To bring about a cease fire that ends the fighting. And that can stop the deaths. An innocent civilians both in Gaza and in Israel so secretary Kerry will meet with the allies and partners. I've instructed him to push for an immediate cessation of us hostilities. Based on their return to the November 2012 cease fire agreement. Between Israel and Hamas in Gaza. The work will not be easy. Obviously. There. Are enormous. Passions involved in this and some very difficult. Strategic issues involved but nevertheless. I've asked John to do everything he can that help facilitate. A cessation in hostilities. We don't wanna see any more civilians getting killed. We respect to Ukraine. It's now been four days cents Malaysian airlines flight seventeen was shot down. Over territory controlled by Russian backed separatists. In Ukraine. Over the last several days. Our hearts have been capsule would broken. As we learn more about. The extraordinary. And beautiful lives that were lost. Men. Women. And children. And infants. Who were killed so suddenly and so sentences. Our thoughts and prayers continue to be with their families around the world were going through. Just unimaginable grief. I've had the opportunity to speak to a number of leaders around the world whose citizens. Were lost on this flight and all of them remain in the state of shock but frankly also in the state of outrage. Our immediate focus. Is on recovering. Those who were lost. Investigating. Exactly what happened. And putting forward to the facts. We have to make sure that the truth is out. And that accountability exists. International investigators. Are on the ground they've been organized I've sent teams other countries sent teams. They are prepared they are organized to conduct what should be. The kinds of protocols and scouring. And collecting of evidence. That. Should follow any. The international incidents like this and what they need right now is immediate and full access to the crash site. They need to be able to conduct a prompt and full and unimpeded. As well as transparent investigation. And recovery personnel have to do the solemn. And sick for work of recovering the remains. Of those who were lost. Ukrainian president port Genco has declared a demilitarized zone around the crash site. As I said before you have an international teams already in place prepared to conduct the investigation and recover. The remains of those who have been lost but unfortunately the Russian backed separatists who control the area continue to block the investigation. They've repeatedly prevented international investigators from gaining full access to the wreckage. Investigators approached they fired the weapons into the air. He separatists are removing evidence from the crash site all of which begs the question what exactly are trying to hide. Moreover these Russian backed separatists are removing bodies from the crash site. Often times without the care. That we would normally expect from a tragedy like this. This is an insult to those who've lost problems. It's the kind of behavior that has no place. In the community of nations. Now. Russia has extraordinary influence over these separate us no one denies that. Russia has Earth's urged them on Russia has trained them. We know that Russia has armed them would military equipment and weapons including anti aircraft weapons. Key separatist leaders are Russian citizens. So given its direct influence over the separate us. Russia and president prudent in particular. Has direct responsibility to compel them to cooperate. With the investigation that is the least that they can do. President prudent says. But he supports a full and fair investigation and I appreciate those words but they have to be supported my actions. The burden now is on Russia to insist that the separate us stop tampering with the evidence. Grant investigators were already on the ground immediate. Full and unimpeded access to the crash site. The separate us and the Russian sponsors are responsible for the safety. Of the investigators doing their work. And along with our allies and partners. We will be working this issue at the United Nations today. More broadly as I've said throughout. This crisis. And the crisis in Ukraine general. I've said this directly to President Putin as well as publicly my preference continues to be finding a diplomatic resolution. Within your cracked. I believe that can still happen. That's my preference today and will continue to be my preference but. If Russia continues to violate Ukraine's sovereignty and backed peace efforts. And these separatist become more more dangerous and now our wrists not simply to the people inside of Ukraine. But the broader international community. That Russia will only further isolate itself from the international community and the cost for Russia's behavior will only continue to increase. Now it's time for President Putin and Russia. To pivot away from the strategy that they have been taken. And get serious about trying to resolve. Hostilities within Ukraine in a way that respects Ukraine's sovereignty and respects the right of the Ukrainian people to make their own decisions about their own lives. And time is of the essence. Our friends and allies need to be able to recover those who were lost that's the least we can do. That's the least that decency demands. Families deserve to be able later loved ones to rest with dignity. The world deserves to know exactly what happened. And people of Ukraine deserve to determine their own future. Thanks. President Obama speak on it while house on the South Lawn. White House correspondent Peter Mayer again as you alluded to prior to mr. Obama's remarks he did did put the pressure on the Russians. Well he certainly did several times during this brief statement which again came from just outside the Oval Office the president said. Time is of the essence when it comes to. The proper care and recovery of the bodies from the scene. And he said it is time for Russia's Putin and Russia itself to pivot away from the path that has been following a when it comes to the support. Of the separatists in fact dead Dave these were the strongest remarks that the president has made. Since the downing of a Malaysian flight to at seventeen Arab Malaysian airlines flight seventeen. He asked what exactly are they meaning the separatists and there Russian supporters trying to hide he said we have to make sure the truth is out and accountability exists. The US will now makes this case again at the United Nations today. And elsewhere around the world. You concede that from the statements made by the president and other world leaders today. That intense pressure is building on the Russian President Putin. The British prime minister David Cameron also had some very very strong remarks today. About day in his words cronies and all oligarchs and Moscow running the show in Ukraine. So again as he has almost every day since the downing of that airliner President Obama Dave has again spoken out. And now we switch to CBS's Kenny McCormick in key Evan cameo. You've been following what's been happening on the ground there with respect to getting those bodies and getting them to a place where they can be identified. She yet the that's right if the president. Equipment into key aspects of this that that is the recovery of the bodies getting them identified to getting them repatriated. Secondly the evidence on the ground there that it not be tampered with any more than it has spent. We talked some Dutch investigators come in today they were able to inspect some of these train cars these refrigerated train cars. That all the bodies of these victims. But they also did you go to the crash site but at every step. They were followed by armed separatists and I think that's what the president was alluding to it in fact we've heard from. Dutch investigators to date had been appealing to the rebels to allow these train cars to leave this rebel held town to date time but obviously of the essence. These refrigerated cars these are bodies that have been lined up the field for days they need to get them to where they did what they have X. Experts who can examine them identify them and send them home to their families. CBS's Cameron McCormick in Kiev Ukraine. I'm Dave Barrett CBS news for Peter Mayer this has been a CBS news special report.