Russia has been holding last-minute military exercises near commercial shipping lanes in the Black Sea that threaten to strangle Ukraine's economy, according to an internal document from Ukraine's ministry of defense reviewed by Axios.

Why it matters: With the eyes of the world on the massive buildup of troops in eastern Ukraine, the leaked memo shows Russian forces escalating their presence on all sides of the Ukrainian border.

Zoom in: On Friday, Russia announced it intends to block foreign ships in parts of the Black Sea for military exercises through October — an escalation that a State Department spokesman condemned as an example of Moscow's "ongoing campaign to undermine and destabilize Ukraine."

• Just days earlier, the Pentagon had called off plans to send two U.S. warships to the Black Sea, according to Reuters. An explanation was not provided.
• The leaked Ukrainian document assesses that the total area of Russian military exercises takes up 27% of the Black Sea — a proportion that has steadily crept up, in a sign of efforts to establish de facto control over international waters.
• The Russians are also leveraging civilian infrastructure for military purposes, according to Ukraine. The document says that Russia has installed radars on natural gas platforms that it seized from Ukraine after the 2014 annexation of Crimea.

Between the lines: Radar systems on civilian infrastructure could allow the Russian military to establish awareness and a presence in areas where it shouldn't be.

• Just this month, Russian state media accused Poland of "provocative" activities near the controversial and nearly completed Nord Stream 2 pipeline in the Baltic Sea.
• A U.S. official who tracks these developments closely said "the weaponization of energy infrastructure in the Black Sea should be a warning sign of what's to come" if Nord Stream 2, which would bypass Ukraine and deliver Russian gas directly to Europe, comes to fruition in the Baltic.
• While Biden has said he opposes Nord Stream 2, he is unlikely to sanction European allies like Germany to stop its last stretch of construction.

The big picture: Much of the concern over Russia's aggression in recent weeks has been directed not at its activities in the Black Sea, but at its border with eastern Ukraine, where the European Union's top diplomat claims more than 150,000 troops have now amassed.

• The leaked document shows that Russian forces are escalating their presence on all sides of the Ukrainian border with units that boast a vast array of capabilities, including many that suggest more sinister intentions than a simple show of force.
• The document suggests that Russia's actions could be designed to distract from domestic problems ahead of legislative elections in September, or to counter NATO exercises and bully Ukraine into reversing its "positive political developments."
• But it also finds a "high probability" that Russia may be seeking to provoke Ukrainian forces in order to create a pretext for a military incursion, as it did in Georgia in 2008.

For the record: In response to a request for comment, the Russian Embassy in Washington directed Axios to an April 15 briefing by foreign ministry spokeswoman Maria Zakharova, who accused NATO countries of "encouraging Kiev’s militarist sentiments."