Clashes intensified yesterday as Ukraine’s interim government began to assert itself with so-called “pro-Russian separatists” in its eastern provinces. Yesterday, Ukraine claimed that it had received support from the US to act, and attempted to dismantle roadblocks in Slavyansk. Five people died in the violence that followed, and all sides are accusing the others of responsibility:

Ukraine’s military launched assaults to retake rebel-held eastern towns on Thursday in which up to five people were reported killed, a move Russian President Vladimir Putin warned would have “consequences”. …

In Slavyansk, a flashpoint east Ukrainian town held by rebels since mid-April, armoured military vehicles drove past an abandoned roadblock in flames to take up position, AFP reporters saw.

Shots were heard as a helicopter flew overhead, and the pro-Kremlin rebels ordered all civilians out of the town hall to take up defensive positions inside.

“During the clashes, up to five terrorists were eliminated,” and three checkpoints destroyed, the interior ministry said in a statement. Regional medical authorities confirmed one death and one person wounded.

Earlier Thursday, Ukrainian special forces seized back control of the town hall in the southeastern port city of Mariupol with no casualties, Interior Minister Arsen Avakov said. Separatist sources confirmed the loss of the building in the port city, whose population is 500,000.

That may prompt a response from Russia. Yesterday, Sergei Lavrov warned that Ukraine could expect the same treatment Georgia got in 2008 if it attacked ethnic Russians, a threat that the interim government in Kyiv certainly has had in mind since coming to power. Later, he made the threat even more explicit:

Lavrov didn’t say on Wednesday that any military intervention was imminent, but he didn’t rule it out, either.

“Russian citizens being attacked is an attack against the Russian Federation,” he said.

The US didn’t remain silent, either. Earlier today, from his tour of Asia, Barack Obama warned Russia that more sanctions will be coming. However, coming in nearly the same breath as his claim of victory on Syrian chemical weapons, it might be a little difficult for Vladimir Putin to take it too seriously:

If the sanctions talk doesn’t phase Putin, then another Obama move may. State-owned propaganda channel RT took a good, long look at the arrival of American troops in Poland in the last 24 hours — with more coming to the Baltic states that border Russia:

The first American troops arrived in Poland on Wednesday, after Washington said it was sending a force of 600 there and to the Baltic states amid rising tensions with Russia over Ukraine.

Some 130 soldiers from the 173rd Airborne Brigade — nicknamed “Sky Soldiers” — touched down early afternoon in Swidwin, in the northwest of the country, and were welcomed by Poland’s defence minister.

“Every day we work on the defence of our country but in a world that is changing, and that is full of threats, we need strong and steadfast allies such as the United States and NATO,” Minister Tomasz Siemoniak said under a cloudy sky.

The troops, who are usually based in Vicenza, Italy, arrived at the base on two Hercules transport planes.

A further 450 US troops will be deployed in the next few days in the ex-Soviet Baltic states Estonia, Latvia and Lithuania, following Washington’s announcement Tuesday that it would increase its presence in the region to reassure its NATO “allies and partners”.

NATO apparently needs plenty of reassurance:

Today’s NATO, hollowed out by years of European military cuts and deployed mostly to help fight far-off battles in places like Afghanistan and Libya, is no longer as prepared to counter a newly assertive Kremlin, its own leaders acknowledge.

Western European members of NATO may regard the conflict over Ukraine as remote, an annoying threat to their business ties to Moscow, said Artis Pabriks, who was Latvia’s defense minister until he stepped down in late January. “But for us, it’s not about money, it’s existential,” he said. “You guys may remain with your freedoms, but we may not, so it’s different.”

NATO itself is awakening to the altered circumstances. Ukraine, said Maj. Gen. Andrew M. Mueller, who commands NATO’s fleet of 17 surveillance planes, “made us re-emphasize the mission we were built for.”

“We’re augmenting NATO defenses inside NATO,” he added. “We’d gotten away from that a bit with Afghanistan and Libya.”

But it will take more than a change of emphasis to re-energize a military alliance that has badly eroded since 1989. The United States is responsible for 75 percent of NATO military spending, and only a handful of European countries meet the alliance’s target of having military budgets of 2 percent of gross domestic product.

Putin has made NATO relevant again, a development he may end up regretting. The costs of this adventure are escalating for Putin, even if only incrementally. The question will be whether he takes the West seriously enough to stop before he sends troops over the Ukrainian border, or possibly that he takes the West so seriously that he feels he has no other choice but to grab eastern Ukraine.