Troops to diplomacy: What you should know about Ukraine-Russia crisis

Tensions spiked anew over Ukraine on Thursday with conflicting claims over whether Russia had drawn down troops it has been massing for weeks around Ukraine, escalating hostilities in Ukraine's separatist-controlled east and intensified diplomacy.

U.S. President Joe Biden warned there is still a very high risk of a Russian invasion within several days. And, in what the United States described as an unprovoked move, Russia expelled a senior U.S. diplomat in Moscow.

A day after Moscow said it was returning troops to bases, the NATO allies said Russia is actually building up forces near Ukraine. At the same time, Ukraine and the Russia-backed rebels in its east accused each other Thursday of intensive shelling along the line of contact in Donetsk and Luhansk.

U.S. Secretary of State Antony Blinken, on his way to an annual security conference in Germany, was rerouted to the United Nations to promote a diplomatic solution.

Here's a look at what is happening where and why:

WHAT WE DO AND DON'T KNOW ON THE GROUND

Russia says it moved its troops away from the conflict zone. But NATO allies say constant movements mask their true intentions.

NATO allies accuse Russia of misleading the world by saying some 7,000 troops were being returned to bases, but instead moving in thousands of new ones.

Maxar Technologies, a commercial satellite imagery company that has been monitoring the Russian buildup, reported continued heightened military activity near Ukraine, including a new pontoon bridge and a new field hospital in Belarus.

Russia has massed an estimated 150,000-plus troops on three sides of Ukraine in recent weeks, but denies it is plotting an invasion.

NATO Secretary-General Jens Stoltenberg said Russia has enough troops, enough capabilities, to launch a full-fledged invasion of Ukraine with very little or no warning time, and that is what makes the situation so dangerous.

The fact that you're putting a battle tank on a train and moving it in some direction doesn't prove a withdrawal of troops, he said. It has to be a meaningful withdrawal, a meaningful de-escalation.

Shelling along the border in Ukraine's separatist-controlled east also has fueled speculation that Russia might be creating a pretext to invade Ukraine. A sharp increase in skirmishes in recent days raised that specter.

In the latest incident, separatist authorities in the Luhansk region reported an increase in Ukrainian shelling. The Ukraine military said it had not fired back after its forces were shelled. They said the shells also hit a kindergarten, wounding two civilians.

WHAT DO SATELLITES SHOW?

Widely available commercial satellite imagery of Russian troop positions bracketing Ukraine provides a bird's-eye view of an international crisis as it unfolds. But the pictures, while dramatic, have limitations.

High-resolution photos from commercial satellite companies in recent days confirmed that Russian forces are arrayed within striking distances of Ukraine. But they could not provide conclusive information about net additions or subtractions of Russian forces or reveal when or whether an invasion of Ukraine would happen. In such a fluid crisis, even day-old satellite photos might miss significant changes on the ground.

The U.S. military and intelligence agencies can piece together a better picture of what's happening by combining satellite imagery with real-time video as well as electronic information scooped up by aircraft such as the Air Force's RC-135 Rivet Joint, not to mention information gathered from human sources.

THE DIPLOMATIC FRONT

As EU and NATO officials sent out assurances that there's still room for diplomacy, Russia expelled the second-highest U.S. diplomat in Moscow.

Washington said the expulsion of U.S. deputy chief of mission Bart Gorman was an unprovoked escalation in tensions. We are considering our response, the State Department said.

HOW DOES THE UNITED STATES SEE A RUSSIAN INVASION UNFOLDING?

Blinken went before the U.N. Security Council on Thursday to sketch out how Washington contends a Russian attack would unfold, revealing conclusions of U.S. intelligence in a strategy the United States and Britain have hoped will pre-empt any Russian invasion planning. The United States has declined to reveal most of the evidence underlying its claims on Russia's planning.

A sudden, seemingly violent event staged by Russia to justify invasion would kick it off, Blinken told U.N. diplomats. We don't know exactly the pretext, he said a so-called terrorist bombing inside Russia, a staged drone strike, a fake, even a real attack using chemical weapons.

The military attack itself would open with cyber attacks and missiles and bombs dropping across Ukraine, America's top diplomat said. Painting the U.S. picture further, Blinken described the entry of Russian troops, advancing on Kyiv, a city of nearly 3 million people, and other key targets that have already been identified and mapped out.

U.S. intelligence indicated Russia would target specific groups of Ukrainians, Blinken told the U.N., again without giving details. In an implicit nod to Secretary of State Colin Powell's appearance before the Security Council in 2003, when Powell cited false U.S. intelligence to justify the U.S. invasion of Iraq, Blinken added: Let me be clear. I am here today not to start a war, but to prevent one.

WHAT IS MOSCOW SAYING?

Russia on Thursday reaffirmed its demand for the U.S. and its allies to keep Ukraine out of NATO but held the door open for talks on a range of security issues.

The Russian Foreign Ministry handed over its formal reply to the U.S. and NATO security proposals and later published it on its website.

The document again denies Western claims that Russia has an intention to invade Ukraine, but repeats that NATO's expansion to Ukraine and other ex-Soviet nations would be a red line for Russia.

It says Moscow will continue pressing its demands for no further NATO expansion and for the alliance to roll back its forces from Eastern Europe, and could take unspecified military-technical measures if the West continues to ignore them.

At the same time, it says Russia is ready to discuss measures to enhance security in Europe by negotiating limits on missile deployments, restrictions on patrol flights by strategic bombers and other confidence-building steps provided they are discussed in conjunction with Moscow's main proposals.

HOW ARE UKRAINIANS REACTING?

Ukrainian President Volodymyr Zelenskyy suggested that NATO membership is a distant dream for his country, blaming both opposition from Russia and from some unidentified NATO members.

It is not the Ukrainian people who choose when we will be (in NATO), because it depends not only on us: 30 countries must unanimously agree on this decision, Zelenskyy said.

WHAT IS NATO DOING?

Stoltenberg, in opening a meeting of the alliance's defence ministers in Brussels, said Russia has yet again demonstrated its disregard for the principles underpinning European security, and its ability and willingness to threaten the use of force in pursuit of its objectives.

U.S. Defence Secretary Lloyd Austin told reporters in Brussels that Russia is moving troops close to the border, flying in more combat and support aircraft.

We see them sharpen their readiness in the Black Sea. We even see them stocking up their blood supplies,? he said. You don't do these sort of things for no reason, and you certainly don't do them if you're getting ready to pack up and go home.?

Meanwhile, the alliance is bolstering its eastern regions.

The U.S. has started to deploy 5,000 troops to Poland and Romania. Britain is sending hundreds of soldiers to Poland and offering more warships and planes. It also is doubling the number of personnel in Estonia and sending tanks and armored fighting vehicles. Germany, the Netherlands and Norway are sending additional troops to Lithuania.

The White House said Biden would discuss the matter with trans-Atlantic leaders in a phone call Friday afternoon. The Canadian prime minister's office said the call would include the leaders of Canada, France, Germany, Italy, Poland, Romania, the United Kingdom, the European Union and NATO.

The U.S. Senate voted overwhelmingly Thursday night to show unwavering support for an independent Ukraine and condemn Russian military aggression toward its neighbour.