Russia claims it killed 5 Ukrainian troops crossing border as U.S. warns of "false flags"

Russia claimed Monday that its forces had killed five Ukrainians with anti-tank weapons after their vehicles crossed into Russian territory, which Ukraine denied. The head of Russia's FSB intelligence service later claimed one Ukrainian soldier had been captured.

Why it matters: U.S. and Ukrainian officials have vehemently denied claims that Ukraine would launch attacks on Russia soil at a time when 150,000 Russian troops are massed on the borders, but fear they're part of the Kremlin's efforts to justify an imminent invasion.

• Russian state media claimed the Ukrainians that were killed had been on a "sabotage" mission, and also reported that Ukrainian shells had destroyed a border post on Russian soil.
• Ukrainian Foreign Minister Dmytro Kuleba denied both allegations and called on Russia to "stop your fake-producing factory now."
• The U.S. Embassy in Ukraine tweeted: "Russia’s execution of transparent, hackneyed plots to justify an invasion would be laughable if they weren’t so destructive and dangerous."

Zoom out: Pro-Russian separatist leaders in eastern Ukraine have asked Russian President Vladimir Putin to send military assistance and recognize the independence of their breakaway republics, Russian state media reported Monday.

• The Russian-backed separatists have been battling Ukrainian forces since 2014, when they proclaimed independent "republics" in Donetsk and Luhansk. Because they don't control all of the territory they claim, recognition by Russia could actually be a de facto declaration of war.
• It could lay the groundwork for future Russian annexation of the territory. Recognition would also amount to a withdrawal from the Minsk Accords, which are viewed as the best chance to bring to peace to the war-torn Donbas region.
• Putin has until now downplayed the possibility of recognition and insisted that he wants the Minsk Accords to be implemented, but he held an extraordinary televised meeting of his Security Council on Monday to consider the proposal.

The big picture: President Biden and Putin agreed "in principle" on Sunday night to French President Macron's proposal to hold a leaders summit, but both sides have downplayed the likelihood of this happening.

• "Of course President Biden said yes, but every indication we see on the ground right now in terms of the disposition of Russian forces is that they are, in fact, getting prepared for a major attack on Ukraine," national security adviser Jake Sullivan said on NBC's "Today" on Monday morning.
• In televised remarks during Russia's Security Council meeting, Putin claimed Macron had told him Biden had shifted his position on Russia's security demands in Europe, without providing any details.

What to watch: Senior officials at the Security Council made a case for recognizing the republics and sending in troops to "defend" the Russian citizens in eastern Ukraine — attempting to position Russia as the victim of escalation that is outside of its control.

• After asking if there were dissenting views — and finding none — Putin said he would make a decision on recognizing the separatist republics on Monday.