As Chinese incursions continue, Taiwan says it will fight "to the very last day" if Beijing attacks the island democracy of nearly 24 million people. Taiwan Foreign Minister Joseph Wu said as much in remarks to reporters Wednesday in Taipei, according to Reuters. 

That rhetoric of escalation comes as the U.S. Navy just sent its guided missile destroyer USS John S. McCain through the Taiwan Strait.

About those incursions: China flew at least a dozen "fighter jets into Taiwan's air defence zone on Wednesday in a stepped up show of force," Reuters reports, with China's air force now "making almost daily forays in Taiwan's air defence identification zone." 

Bigger picture: The Chinese military is exercising east and west of the island, and has placed its aircraft carrier Liaoning east of Taiwan, complicating potential approaches by Japan's military, CNN reports.

However, former U.S. Navy captain Thomas Shugart told CNN, "A Chinese carrier operating east of Taiwan is not particularly valuable being used like that, as it could be quite vulnerable operating that far out — in SSN-infested deep water and beyond China's integrated air defense/SAM umbrella."

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Also nearby: The U.S. Navy's USS Theodore Roosevelt Carrier Strike Group, which is exercising in the South China Sea this week — and for the second time this calendar year, according to the Navy. (Here are some photos of flight operations there, posted Tuesday to Twitter.) 

Said the carrier group's commander, Rear Adm. Doug Verissimo: "We have demonstrated our commitment to the rules-based order in the Indo-Pacific region by operating with our friends from South Korea, Japan, Australia, India, and Malaysia. We look forward to continuing to sail together with all those that embrace our collective vision of security and stability in one of the most important regions in the world."

What next for Taiwan? Its military has planned "eight days of computer-aided war games this month, simulating a Chinese attack," according to Reuters. "A second phase of exercises, including live-fire drills and anti-landing drills, will take place in July, when hospitals would also practice handling mass casualties." 

Iran-Israel shadow war on the high seas. Someone attacked an Iranian cargo ship that's believed to be a spy ship for the Iranian Revolutionary Guard Corps, Joyce Karam of The National reported. The ship (Saviz) was somewhere off the coast of Djibouti when it was hit; it's now somewhere in the Red Sea.
IRGC's news points the finger at Israel and says limpet mines were used in the Tuesday attack, which hit the generic cargo vessel, according to Tehran's state-run Tasnim news agency.
So, whodunnit? According to the New York Times, "an American official said the Israelis had notified the United States that its forces had struck the vessel at about 7:30 a.m. local time" on Tuesday.
That U.S. official "said that the Israelis had called the attack a retaliation for earlier Iranian strikes on Israeli vessels" like the Helios Ray on February 28, or the MV Lori on March 25. (For a bit more on all that, see this Times reporting from March 26.)

Back stateside, a U.S. Navy medic shot two fellow sailors before fleeing a few miles west to an Army base, where he was shot and killed by gate guards at Maryland's Fort Detrick, home of the Army's Futures Command.
The medic drove past Detrick's guards and through the entrance, making it about half a mile in the base before he was gunned down, the Associated Press reported Tuesday. 

This week we learned America's top five recipients of U.S. arms sales in 2020, according to the Center for International Policy. Each of the following countries benefited from an overall 59% year-over-year increase in U.S. weapons sales, which totaled nearly $111 billion in 2020. Those top five recipients are:

1. UAE ($24.1 billion)
2. Japan ($23.2 billion)
3. Finland ($12.5 billion)
4. Switzerland ($8.8 billion)
5. Taiwan ($5.9 billion)

In terms of contractors, Lockheed Martin, Boeing, and Raytheon Technologies led the way, according to CIP. "The three firms taken together were the primary suppliers in deals worth $87 billion, more than three-quarters of the value of U.S. arms offers for 2020."
Half of last year's deals were for Lockheed Martin's F-35, and those went "to just five countries: Japan, Finland, the UAE, Switzerland, and Singapore."
The top regional recipients of U.S. arms sales in 2020 were:

• The Middle East and North Africa, which increased "from $25.5 billion in 2019 to $39.7 billion in 2020," according to CIP;
• East Asia and the Pacific sales "grew from $27.2 billion in 2019 to $38.4 billion;"
• Europe and Eurasia's arms offers ranked third, and "more than doubled from $11.9 billion in 2019 to $27.9 billion in 2020;"
• Western Hemisphere ranked fourth with 2.4% of American arms sales;
• And South and Central Asia (Bhutan to Kazakhstan) ranked last at 2.2% of total U.S. sales.

Another observation from CIP's analysts: "Overall, arms transfers account for less than one-tenth of one percent of U.S. employment." And that means "the economic impacts of overseas arms sales are primarily of import to one industry — and a number of major contractors within that industry — rather than the economy as a whole."
Why does all this matter? Because we still don't know exactly how the Biden administration will differ from its predecessor, particularly regarding potential "human rights, humanitarian impacts, and long-term strategic considerations over industry concerns in crafting its arms transfer policies." Read over the full report (PDF) here.

Lastly today: "Climate crisis" update. The concentration of carbon dioxide in the atmosphere has reached 418 parts per million, a level not seen in millions of years. As far as we understand, "Humanity has never experienced our planet like this," reports meteorologist and author Eric Holthaus off data produced by the Mauna Loa Observatory in Hawaii.
Why this matters: The warming Earth is changing security calculations around the globe, and perhaps nowhere more than in the Arctic. New or recent strategy documents from DoD, the Navy, and the Army lay out plans to assert "dominance" over this ever-more-accessible region.
But maybe we should concentrate on fixing the problem rather than girding for war? "The most comprehensive way to contain Arctic security issues, and reduce the demand for defense resources, is to address climate change and its immediate consequences for Arctic shipping," argues CNA's Joshua Tallin at Defense One. Read on, here.